I had a similar-ish experience with BT some years ago. Received letters and emails thanking me for ordering another business line with broadband, using my correct name. So I contacted saying it's an error so they cancelled and put a note on that account.
I then received more order confirmations 4 times 8-0.
Cancelled each one.
On the 5th occasion I found they had included for the first time a contact phone number for me that was not mine or even in the same county. Called number- to cut a long story short, it was the owner of a chain of hairdressing shops who had the same (rare-ish) name as me. He had been trying to order lines for a month and BT told him that he had cancelled each time. He had been pulling his hair out ( sorry) and was very grateful. I now have free haircuts if I want to drive 200 miles.
Neither he nor I received an apology from BT. So things can go very wrong, usually with surreal results. The ISPs systems seem to have no process for dealing with such errors.
Hope you get it sorted!
BT Infinity 2, HG612 & Billion 7800N or BT Business Hub 6A: 80/20 synch. Online since 1987. Apples & Macs since 1979. Dreambox fun. Advanced Radio Amateur Licence and an anorak.