Some years ago I wondered about the cost-effectiveness of asking for disconnection of the supply to a flat (it was expected to remain empty for some time, and it annoyed me to have to pay the standing charge).
Recently I received an estimated bill for a different flat which was too high because I was no longer living there, emailed actual figures, and until recently was too busy to visit again to see if a revised bill had been posted. I just received a belated reply to my email, reducing the bill to 1/2 what it was and making threats about this 'overdue bill'.
So I'm again wondering about asking for disconnection. How much would they charge for this, and for later reconnection? It probably involves only pulling a fuse in their supply box. In this case I don't think I seriously mean it (but in future who knows?). Presumably they can't charge for a supply you've asked to be disconnected.