Cell C pathetic

I cancelled my contract when it expired, called and received confirmation that the contract was indeed canceled. This was in May 2021, last week I received a message from VVM that I owe cell c about R1200, how when there are recordings with the consultant from cell C confirming that all was in order and there were no attempts to debit by Cell C from my account since May 2021....how can I be even handed over for a contract that was terminated