Help with bill calculations

Actual gas bill:
3 September 2017 7650 Estimate
4 September 2017 7665 Read
1 October 2017 7696 Read
Meter units used: 46
Energy* 517 kWh @ 2.35 p/kWh £ 12.16

My calculations using your formulas:
Meter units used 46
Volume conversion factor x 1.00
Metric units = 46
Volume correction x 1.02264 = 47.04
Calorific value x 39.3 = 1848.67
Convert to kWh ÷ 3.6 = 513.52
Energy used 513 kWh
Energy 513 kWh @ 2.35 = £12.05

This is showing a discrepancy of 4 kWh (11p)
Can you explain or correct my calculation.

On another point:
Last month an estimate was used which gave an elec reading of 123.3kWh used, although my bill this month reads 223 kWh used, is this bill calculated on 222.7kWh in other words has the .3kWh been taken in to account?

@scudo You’re quite right, using the details on your bill it comes to 513.53 kWh. However, the calorific value quoted on your statement is actually incorrect. The average calorific value for your area during your bill period, and the one used to calculate your kWh value, is 39.57 which brings it into line.

On your other point. We don’t actually bill to decimal places and I can only see 123 kWh on your previous electricity statement, not the 123.3 kWh you quoted.

Alistair, thanks for replying, however I find the answers to be unsatisfactory. On the 2nd point re .3 of a kWh not being used you are incorrect, and I quote from a bulb email:

“The reason for the discrepancy, which I didn’t spot the first time round (apologies), is that the estimated reading on 3rd September was actually 50335.3kWh.
That means that the usage on your statement should in fact read 123.3 kWh.
Then, 123.3 kWh @ 11.6736 equals £14.3935 or rounded up is £14.39.”

On the first point I feel strongly that I should only be charged on the calorific value that you state on my monthly statement, ok if it rises or falls the following month I accept that but to charge a figure other than what you state is morally if not legally wrong.

Although in general terms I am happy with Bulb the billing/statements are becoming a game in trying to match them up to my own calculations. I have had one sample and 2 actual statements and all three have lead to several emails to clarify how the amounts have been arrived at.

Hi @scudo, the bill is showing the calorific value on the date the bill is issued, whereas the bill amount calculation uses an averaged calorific value over the period. Are there any further issues with the billing we can help with?

Thanks
James