Vodacom keep invoicing for cancelled contract

I have cancelled My vodacom account back in October 2021, I was told everything will be finalised once the final payment for the month of October was debited and it was. The next month I received an invoice for the already cancelled contract. I phoned vodacom's cancellations department and they told Me it was an error on their part and that they will sort it out I need not worry. The next month I received another invoice and the debit My account. I phone in again and again they tell Me they are sorry for the error and they will fix it. Last month they debited My account again with double the amount, I was tired of phoning in for the same query every ti.e and reversed the payment from My bank account. Today they sent Me yet ANOTHER invoice.

I am really tired of dealing with them because it seems they do not take cancellations seriously.