@revk I had a similar experience with Bulb and I'll still not sure if they have fleeced me or not. I'm not sure how to check properly either. It's troubling me.
(I also have another issue where they supplied a faulty smart meter in April and still haven't replaced it, suggesting I buy one directly from the manufacturer)
@revk Why they can't send it back to the manufacturer themselves is a mystery they can't be bothered to fix.
But now I'm more worried about the fact they might have backdated charges for the first two years I didn't have a working electricity meter at all!
@revk eon tried to back-bill us for 4 years in the noughties.
I argued we hadn't tried to hide usage, we'd been having meter readings taken and even if (as they claimed) they never got our move-in notification, they can still send bills addressed to the occupier and so the onus was on them to provide a timely bill. They grumbled a bit but caved, so we paid an extra year, spread over 4 (IIRC) years.
So they'll probably try it on but once you show you know the rules they'll accept it.