Andy Wade wrote:
Jonathan Pearson wrote:

I'd contact the regulator - I'm sure they would take a very dim view
of this sort of underhand practice!

Why is it underhand? Price change readings are almost always
estimated; it's perfectly standard industry practice. To demonstrate
malpractice you'd have to show that the estimating algorithm being
used was unfair.
Over the dates given by the OP, it was very much colder during the
second period then during the first, so it's entirely plausible that
the daily gas consumption would be much higher during the second
period. But it's just not worth getting worked up about, because any
error only applies to the difference between the old and new prices. I
calculated, roughly, that if the OP had had an even rate of
consumption, the bill would have been about £1.40 less, even after
adding 5% VAT.
In any case, IME, if you can supply your own more accurate (and
plausible) figure, it will be accepted.

Oh, and the OP seems to have a metric meter.

Rubbish!!!

Scottish power has 5million customers, hence if everyone is chraged an extra
£1.40, then that makes them an additional £7400,000 for trying it on -
hopefully the regulator will throw the book at them!

Jon