Cell C contract cancelled but handed over

I have been a clue t for 16 odd years with couple of contracts. I had 2 data contracts which I canceled at same time of which one was a month to month and even checked and confirmed that is was cancelled. I have been struggling since beginning 2021 to sort out this month to month contract that was canceled that has been handed over to debt company. Call centre says that they don't see anything and legal just never gets back to me, I have called and called and called and emailed and nothing helps. Now that my regular contract is due for upgrade they don't want to assist me because of the account but no one can tell me anything about this account.