Spark Energy gas bill rounding errors

M1960

Prompted by a huge final bill from them ( 90% of which was due to them using vastly inflated meter readings ) I went through my recent bills from Spark Energy in great detail, and noticed that the number of Kwh charged for on the gas bill doesn't match up with the number of Kwh calculated from the formula printed on the bill. In every case I was paying for up to 1Kwh more than I had used. Although only a matter of 5p or so per month, over a large number of customers ( forced into Spark's arms by letting agents such as Reeds Rains ) it would amount to a sizeable sum.

Examples from my recent bills:
Month Units Kwh on bill Kwh from formula
9/11 49 1545 1544.1477
10/11 1 32 31.5132
11/11 35 1103 1102.9626
12/11 41 1293 1292.0419
1/12 38 1198 1197.5023

Is this normal for the gas industry, or are Spark undulging in yet more sharp ( possibly illegal ) practice ?

Terrylw1

Perhaps ask Spark what their rounding policy is.

Are they using standard mathematical rules for rounding where greater than or equal to 0.5 becomes rounded to 1.

I would expect rounding down to avoid the customer spotlight, but with new players...who knows.