Handed over amount has been paid

I received notification last year November that I was handed over to Norman Bissett for my outstanding Nashua Mobile account. This account was paid up in full last year July. I received the paid up letter from Nashua Mobile and sent it through to Norman Bissett, Up to today nothing has been done regarding this matter. I DO NOT OWE ANY MONEY!! Does my paid up letter not mean anything?? I want this outstanding amount to be cleared from my name NOW! Everytime I phone the call centre I am just told that the account has been placed on hold waiting for Nashua Mobile to confirm it was paid up. I don't know how that is going to be confirmed as Nashua Mobile no longer exists!! All the contact people I had on their legal department are no longer there. Can this matter be resolved now! I am not going to pay any amount as I already paid up this account. I expect a letter from Norman Bissett confirming that I no more money on this account!<br> <br> Amanda