Tariff Calculation Puzzle

Geoff_W

I am currently on the First:utility iSave Fixed v16 April 2016 Direct Debit eBill tariff which is coming to an end soon. I am planning to change to the First Fixed April 2017 v7 Direct Debit eBill tariff on Monday 14th when I am within the 49 day period. My Personal Projection for the new tariff is £537 per year based on annual consumption figures of 1,631 kWh for Electricity and 11,590 kWh for Gas. The tariff details (see below) also state that it "includes VAT, a Direct Debit discount of £12 per fuel per year and a paperless billing discount of £12 per fuel per year."

My problem is that I cannot get my calculated figures to tally with the £537 projection unless I take off a further £48 which appears to represent the Direct Debit and Paperless Billing discounts. I have spoken to First:utility and they assure me that those discounts are built into the Standing Charge figures, but I just cannot reconcile the numbers.

Can anyone with a smarter brain than me point out where I am going wrong?

Tariff Details:
Electricity: 10.965p/kWh + 13.830p/day Standing Charge - Annual Consumption 1,631 kWh
Gas: 2.166p/kWh + 15.570p/day Standing Charge - Annual Consumption 11,590 kWh

mbrown965

Electricity
Unit cost: 0.10965 x 1631 = £178.84
Standing cost: 0.1383 x 365 = £50.48

Gas
Unit cost: 0.02166 x 11590 = £251.04
Standing cost: 0.1557 x 365 = £56.83

£178.84 + £50.48 + £251.04 + £56.83 = £537.19

Consumerist

Geoff_W wrote: »

Tariff Details:
Electricity: 10.965p/kWh + 13.830p/day Standing Charge - Annual Consumption 1,631 kWh
Gas: 2.166p/kWh + 15.570p/day Standing Charge - Annual Consumption 11,590 kWh

For what its worth, I agree with the £537.19 above.

Geoff_W

Thanks for all your replies. After seeing your calculations I revisited the formulae in my spreadsheet and discovered my error. I had copied a summation formula from a previous tariff and that had incuded a manual addition of £48 to allow for discounts. Like an idiot I had not spotted the error and added a further £48 in another cell. But thanks to your posts I now see the problem, and yes, my total is now £537.

Consumerist

Geoff_W wrote: »

. . . After seeing your calculations I revisited the formulae in my spreadsheet and discovered my error..

Spreadsheets are a great boon once you've got past being driven mad to get them right. Been there!