Cell C never in the wrong.....not?!!!

October 2024 I cancelled my 20year+ contract. The operated said one debit order will still go off. That was fine, the whole 30day notice. In December they debited again. I only used this specific bank account as they never changed it to my new bank. So with the December debit there wasn't funds in that account, as the weren't supposed to debit. So I get phone call stating I should pay the amount due to them told them I cancelled in October. They phoned me again and the same story. I couldn't remember the precise date. Then they phoned again and say they can not find the recording from the day I cancelled the contract but other recording of the 3rd December. I did not phone in December. No they gave my account to debt collecters. I saw on Facebook that this is a norm for cell c to do this. Original amount was R204 o think now it's R363!! The ons lady said that the cancellation was never loaded and confirmed. I'm still waiting for the cancellation letter and refrence number of that day in October. Worst service ever and if you ask to talk to someone in your mother tongue they just ignore you and say you should speak English for the recordings. It also took them 15 years to update my details on the system. I would like to sort this out as I did my side to cancel the account 30 day prior to the cancellation date. The ons lady even said to me that it's the clients that's wrong and they now how to do their job.....well it doesn't seem like it. I even said I would like to talk to die team leader or manager but the CFO would also help they just said that's can not be done.