Is it illegal for British Gas to use a false meter reading?

[Deleted User]

Good grief! Even if what BG has done is completely wrong it is likely to be a simple error that is easily fixed and nothing illegal. But if the OP has engaged BG the same way they have engaged with members of this forum in an effort to fix this, then I suspect that it is just as likely to be that the OPs approach and/or understanding is flawed as it is to be a problem at the BG end. I suggest the best thing to do is forget all this nonsense about legality, ask BG to explain the bill (or post it here so that members of this forum can) and take it from there.