It is pretty bad that there are no checks in place to stop this from happening.

About 15 years ago I suddenly realised I hadn't received an electricity bill from my supplier for quite a while and when I contacted them they initially weren't very helpful. I tried again only to be told that the address of 'my meter' had been changed and the bills had been going there   They then blamed me for this, I must have contacted them and told them to make the change! Why on earth would I have done that?

They changed the address back and then sent me a bill for the full amount which was a ridiculous amount. I asked for a payment plan, they refused. I got the energy regulator involved and they were about as helpful as a chocolate teapot.

Managed to scrape the money together to pay off the bill and then switched to a different supplier.  I would never go back to that supplier and if anyone asked me to recommend one to them I would tell them which one not to use.