Vodacom failed to cancel my contract in time and claim I owe them

I’ve called Vodacom customer service several times after my contract was finished requesting to cancel the contract but I was told it was cancelled but to find month to month I’m still being debited on my bank account money. I went to Vodacom store store and requested that the contract be cancelled but I was told they can’t do it at the shop and I needed to call customer service on the phone and tell them that I want the contract cancelled. I did call Vodacom customer number and asked them to cancel the contract which I was told it’s now cancelled. I called in immediately the contract expired and went to month to month which was a month of September 2020. I called again October, November, December, January, February, March, and April 2021 till I final decided to record the lady I spoke too because nothing I did or said was taken to consideration or the contract was not being cancelled. I even wrote a complain on Hello Peter complain about the same thing and I was told a customer service agent will call and resolve the matter and no one called after that. Now I’ve been called and told I’ve been handed over because I owe them R660 for 3 months and those months where the months I decided to reverse after money was debited on my account after several times being told the contract was finished. So I didn’t reverse those amounts it means Vodacom where going to still ignore my cancellation request and continued like they’ve been doing and deduct money on my account without cancelling my contract. They only time you decide to act was when I reversed their debit orderers and it got their attention when all along this time I was told the contract was cancelled. I called several time on my number cancelling the contract and I would also like to receive call records from those numbers where I called and cancelled the contract from those months above mentioned but was done. That was going serve as proof that the contract was long time cancelled by me on my side but Vodacom customer services agent failed to cancel on their side and how is that my problem because I don’t work for Vodacom. If you hire unprofessional agents who can’t do their job then it becomes my problem at the end of the day. I’m now being harassed every day by people calling and telling me I owe Vodacom money for a contract that was long cancelled and a mistake done by their agents with poor services. They always ask me for the reference number for cancellation which they never gave me even the last last I spoke to when cancelling my contract she never gave me but just told me that the contract has been cancelled. The last lady I spoke to had to record the call as proof that I did cancel. I need help to sue Vodacom and how do I go on about suing them and clearing my name and the ITC show me as a bad costumer who fails to pay my commitments. Now I’m being listed as a bad payer and it’s affecting my credit score.