Genuinely unsure what to do. Paid gas and electric bill for two years by direct debit at our old (rented) flat, which we left in Jan when we bought a house. Over time the gas usage naturally went down because we were working longer hours and became more economical while saving up deposit wearing woolly jumpers all year round. So wasn't surprised to get a hefty amount back when I closed the account after providing a final metre reading: last bill said I was in credit for about £300, and this was repaid into my account by direct debit in Jan.
Now at new house paying bills with EDF so no further contact with a British Gas until two weeks ago when they sent me a 'final bill' for £450! Called up to investigate and they said I should have noticed I had hardly been paying anything for gas in last three months and was incorrectly charged. I now can't remember how much I paid for gas and how much for electricity and can't log in to account because closed online. Have also had a baby since then and can't find the old paper bills, which I am not even sure I kept during move. Would pay up with some grumbling and difficulty (don't have £450 lying around) if I felt I genuinely owed money but am not sure. I provided meter readings, so how can original amount be wrong? If it is, am I liable? Pissed off by whole thing and especially by suggestion on phone yesterday that I should sign up for a payment plan/ pay off in chunks, as if I am somehow delinquent. Shouldn't they at least a) justify clearly what mistake was made and b) give reasonable period for me to make payment rather than demanding now? Oh, should say I have had about five hassling phone calls in last two weeks since bill issued.