Contract ended, I cancelled, stop billing me for service!

My name is Edzani and I HAD a contract with Vodacom that came to an end in December 2022. I called Vodacom to confirm my cancellation on 11 January 2023 on *** where they told me that my last payment will be 15 January 2023 and from February my number will be prepaid. I was surprised on the 15th of February when they debit the money which was not according to our agreement so I reversed the the money and called them again. And they acknowledge that on the system it shows that I have called for cancellation - BUT IT WAS STILL NOT CANCELLED and the money keeps increasing monthly. They said I should pay the outstanding money to cancel the contract (about R1300), since it keeps increasing. Why should I pay for a charge that was *******ly charged since the contract had ended and i explicitly confrimed and cancelled it? Why should i pay for the incompetence of your team, who after noting that the instruction was there, they still did not cancel. You are now harassing me, on costs that are not mine. Please kindly close my account and cancel this contract that was cancelled in January. I do not have a contract, and i should not be liable for the escalation of a cost that was due to your staff's inability to carry instruction.