Stop taking my money and cancel my contract please

I had a contract with MTN which I cancelled in February 2023 and paid penalty fees. I recieved an email and call confirming that it was cancelled. I called again in April when I noticed that they are still deducting and I still recieved confirmation that it was cancelled and I'm now on prepaid. They even said they give me R10, surprisingly I'm getting friendly reminders that they will be deducting almost triple of the original installment on the 31st of May 2023. I informed them that I'm out of the country and don't need the contract anymore but they still deduct and I'm afraid if there are no funds in my account I might end up being blacklisted and my credit score will be messed up. Every month end money is deducted and this is very unfair. I sent emails and they are now ignoring them but sending pathetic friendly reminders of the next debit order.