I had a similar situation. My lesson from that was that if I can make "my" problem "their" problem, it will resolve itself quick.

In my case, someone had mistyped a meter number (matching mine) when signing a new contract with a power company. I got a message from my existing provider that I would be transferred there. I called the new company to explain that it was a mistake, and they seemed happy to fix it. I had to jump through some hoops (get a key to the power panel for the building to take a picture of my meter and stuff), but thought it was okay to get it resolved.

But it didn't work, later I got a letter addressed to the apartment, saying I owned the new company money. I gave them a call, and they didn't really want to fix it, just get their money, and make me do additional stuff to prove I hadn't signed with them. It was then I could say something along the line of "We don't have a contract, which is YOUR problem. As far as I'm concerned I'm getting free electricity until you fix this". Of course I could only say this because legally they can't cut the power here during winter.

But when it became their problem of losing money, it was fixed without issues.