When we moved to our house there was a prepayment electric meter fitted. For one reason or the other we never got round to getting on a quarterly bill (mainly British Gas been nigh on impossible to get through to for this reason). So with the energy price rises we were naturally a bit worried about the cost. Gas is not an issue as we're on a fixed rate until the end of next year. To try and avoid a massive jump since 31st March I've been keeping a close eye on our electric spending. Somehow we're spending less! I have been more careful switching lights off and not leaving things on stand by but it doesn't make sense. I can't check our usage properly as BG haven't been able to provide this properly since Feb (conveniently). So I had a look at my meter and realised it still has the old tariff on it. My app shows the new one. I checked over night and am 99% sure I'm been charged the old standing charge. I contacted BG and told them as I don’t want to inadvertently run up a bill. But they said no you're on new tariff. Against my better judgement I argued with them. They checked again and said there's no problem. But experience tells me this particular team will say anything to get you off phone or live chat without actually resolving anything. So my question is if a prepayment meter is undercharging me and I've told them can they charge me later? Surely the whole point of prepay is so you can't run up a debt?