Bought a flat which was registered to British Gas already (the previous owner forgot to close their account). That was fixed without issue. I gave the details of the flat since I don't have access to meter and was told my bill would be £40/month. 6 months later, after a review, I was around £120 in credit (i.e. I'd been overpaying based on my usage). Bill didn't change though. Another 6 months later, I get a letter saying my bill was going up to £93/month and that I was £100+ pounds in debit. Confused, I called BG to ask what was going on - they genuinely couldn't tell me, their system apparently doesn't give any details. But they said they could bring my bill down to £67/month. For context: I live in a small 1 bed flat. A single radiator in the living room is enough to heat the place and only goes on when a jumper isn't enough to get warm. There's not a chance in hell I'm using £67 worth of electricity every month, never mind £93. Told them that's a joke and I got on Uswitch and changed supplier immediately. Stay well clear of BG would be my advice.