Bill calculations. How accurate are online calculators? (Final bill disagreement -workings inside)

JustAnotherSaver

I've had to go over a years worth of energy as i felt like i shouldn't owe Tonik what I seem to. By the end of this maybe i do or maybe i'm better off. We shall see.

2 things stand out though - an online calculator doesn't tally with their numbers, which is why i ask how accurate they are.

Also they claim i didn't pay in September. My bank statement says i did.

3 Oct '19 - 2 Aug '20

ELECTRICITY: 2983 kWh @ 16.11p/kWh = £480.56 (all rates p/kWh remain the same except at the end)

standing charge for 305 days @ 18.56p /day = £56.60

GAS: 857.3 m3 / 39.5 calorific value ..... billed at 9630.7 kWh @ 3.86p/kWh = £371.74

   yet https://www.energylinx.co.uk/gas_meter_conversion.html states the gas converts as 9619kWh (though I don't know the correction factor).

standing charge for 305 days @ 17.82p/day = £54.34 (all standing charges remain the same except at the end)

Energy cost = £852.30

Standing charge cost = £110.94

Dual Fuel Discount = £31.72

VAT = £46.57

TOTAL = £978.09.

Payments/Credits = 10 payments @ £80.05

£9.91 in "interest credit"

TOTAL = £810.41.

OWE: £167.68

• I wonder about this online calculator difference. It wont make a huge difference but it's not the point. I wonder why there's a difference.
• I've absolutely no idea why there wasn't a payment taken in March 2020. I've checked my bank statement and this has been confirmed. 
• Also not sure why I appear to have been paying off at a rate that is clearly putting me in debit.

3 Aug '20 - 31 Aug '20

ELECTRICITY: 267kWh = £43.01

Standing charge 29 days = £5.38

GAS: 28.7 m3 / 39.6 calorific value

322.8 kWh (online calculator matches) = £12.46

Standing charge 29 days = £5.17

Energy Cost = £55.47

Standing charge cost = £10.55

Duel Fuel Discount = £3.02

VAT = £3.15

TOTAL = £66.15

Payments/Credits = 1 payment @ £80.05

£1.57 in "interest credit)

TOTAL = £81.62

OWE: £152.21

1 Sept '20 - 1 Oct '20

ELECTRICITY: 305kWh = £49.14

Standing charge 31 days = £5.75

GAS: 50.0 m3 / 39.5 calorific value

561 kWh (online calculator matches) = £21.65

Standing charge 31 days = £5.52

Energy Cost = £70.79

Standing charge cost = £11.27

Duel Fuel Discount = £3.22

VAT = £3.94

TOTAL = £82.78

Payments/Credits = NONE.

OWE: £234.99

• So this is saying once again that I missed a direct debit payment, this time in September 2020. Once again I go to check but on my bank statement there in black and white is a direct debit of £80.05 to Tonik on 3rd September. So i'll bracket what I believe I owe after what their workings have me owing.
• Also not sure why for all these other bills i have received "credit interest" but on this one I haven't.
  

OWE: £234.99 (£154.94)

2 Oct '20 (1 day only)

ELECTRICITY: 9.4kWh = £1.51

Standing charge 1 day = £0.19

GAS: 2.0 m3 / 39.6 calorific value

22.5 kWh (online calculator matches) = £0.87

Standing charge 1 day = £0.18

3 Oct '20 - 9 Oct '20

ELECTRICITY: 108.6kWh @ 16.88p/kWh = £18.33

Standing charge 7 days @ 25.55p/day = £1.79

GAS: 25.0 m3 / 39.3 calorific value

279.1 kWh (matches) @ 3.00p/kWh = £8.37

Standing charge 7 days @ 29.19/day = £2.04

Energy Cost = £29.08

Standing charge cost = £4.20

Duel Fuel Discount = £0.10

VAT = £1.66

TOTAL = £34.84

Payments/Credits = £24.13 (apparently this is marked as offset bill and a reference number given - 3rd November 2020).

OWE: £245.70 (£165.65)

• So this is also saying that no direct debit payment was made in October 2020. I have checked this and this is incorrect. 5th October a direct debit payment of £80.05 is showing on my statement to Tonik. I have checked to see if any payment went out in November as i had then cancelled my direct debit once they ceased trading - no November payment. So by my calculations...

OWE: £85.60

Which if March's direct debit had been taken would've left just £5.55.

Interestingly, Tonik's "final bill" for me sits at £189.78 which doesn't match any of the workings i went through yet the numbers are based on what they've charged me as per my online bill.

I know it's a bit long winded but i needed to go through it bill by bill in order to make sense of it.

I'm hoping someone has stuck with me throughout this post and can point out if i've gone wrong anywhere. I'm hoping i haven't and that Tonik have messed up. Clearly by saying i haven't paid in 2 months when my bank statement can prove i have. Still, i'm not sure how they come to their final bill total either.

Neil_Jones

There is no substitute for a spreadsheet of your own, documenting the readings as you go.  Do it properly it'll even work out your next bill for you!

The gas calculation formula is on the bottom/back/second page of your gas bill.  Units Used as reported at the meter x Metric Conversion (1 for metric, 2.83 for imperial), x Calorific Value (typically 39.3) x Volume Correction (typically 1.02264)  ÷ 3.6.  Typically rounded to the nearest whole number.

molerat

The calorific value can be downloaded from here https://mip-prd-web.azurewebsites.net/DataItemExplorer/Index.  Download the information for the relevant dates and region and take the average rounded down truncated to one decimal place.  Got my gas bill today and absolutely spot on with my spreadsheet using a CV of 38.6. 

edited for pedantry

JustAnotherSaver

Thanks for the feedback. 
Going forward I think I will implement something like that. 

With the problem at hand though, I'm not asking you to crunch all the numbers as there's quite a few but would you be in agreement that Tonik have messed up or have I likely got it wrong somewhere? 

To come to the end figure that I did, all I did was accept all their numbers on the bills they provided, including the one where the online calculator didn't agree with their gas workings (I still went with their own numbers and not the online calculators). 

What I didn't accept was that they said I had not paid 3 months - March, September & October. My bank statement shows that I paid for 2 of those 3 months.

What is baffling me though is that whether we go with those 2 months being included or not, neither would actually result in what their final bill is for me. 

JustAnotherSaver

Oh and they're also not responding. They forward you to SP and then SP tell you to go see Tonik.
So you're just going round in circles. 

[Deleted User]

molerat said:

The calorific value can be downloaded from here https://mip-prd-web.azurewebsites.net/DataItemExplorer/Index.  Download the information for the relevant dates and region and take the average rounded down to one decimal place.  Got my gas bill today and absolutely spot on with my spreadsheet using a CV of 38.6. 

CV is never rounded. It is the average CV across the whole of the billing period Truncated to one decimal place. For example, an average CV of 39.66 would be truncated for billing purposes to 39.6.

purplepixi

Not really a maths thing, but they don't always get it right. We once changed company and had a £5,000 bill for 2 weeks of electric. When we phoned them we were asked "how would you like to settle your account" 
After a lot of investigation it was the fault of the guy who read the meter, he put the wrong numbers in. But we had to fight to get it sorted.

maisie_cat

Online calculators are too simplistic, I have a spreadsheet going back to 2006 and it is accurate. In addition it has helped us reduce our electrcity consumption by 5kwh a day over that period

[Deleted User]

Hi,

all you need is a wee spreadsheet, simple example.

Just input your own data, and formulae.

Cost will be (Days x St Ch) + (Used x unit price) +VAT @5% on St Ch only if already included in unit price.

Best to update readings when DD has been paid for accurate balance.

Talldave

JustAnotherSaver said:

Thanks for the feedback. 
Going forward I think I will implement something like that. 

With the problem at hand though, I'm not asking you to crunch all the numbers as there's quite a few but would you be in agreement that Tonik have messed up or have I likely got it wrong somewhere? 

To come to the end figure that I did, all I did was accept all their numbers on the bills they provided, including the one where the online calculator didn't agree with their gas workings (I still went with their own numbers and not the online calculators). 

What I didn't accept was that they said I had not paid 3 months - March, September & October. My bank statement shows that I paid for 2 of those 3 months.

What is baffling me though is that whether we go with those 2 months being included or not, neither would actually result in what their final bill is for me. 

If you don't use the same Calorific Value as the supplier it's obvious the figures will be different.  My spreadsheet has a column for CV which gets a new entry when the supplier changes it. But even then, because my spreadsheet is in weeks and the supplier's bill is by month, our figures will never match 100%, but a few kWh gas difference is negligible and not worth stressing about.

Petriix

I was with Tonik for a year. Their system (or the way it was used) was incapable of creating an accurate bill and there was always a discrepancy. Mine was only a few ££s out but it was like banging my head on a wall trying to get them to resolve it. They were never able to make their figures add up and it was impossible to recreate their calculations.

Definitely stand by your own calculations to ensure that the final bill is in the right ballpark. I wouldn't bother arguing over a few pence, but if they've lost some of your DD payments then you need to dispute it.