Keeps debiting account after contract is cancelled, with cancellation confirmation from them

I ended my home wifi contract with MTN and received a confirmation email from a lady Judy Naidoo. The service was ended on 21 April 2023. In May they again debited an amount of R858 from my account. I went into the bank to reverse the debit order which cost an additional R40.

Today 7 June, they once again debited the amount of R869.50 from my account, which I will have to reverse again because ABSA didn't remove the debit order properly on their side as requested.

From May I have received no return emails from them explaining why they keep debiting my account or how they can fix this. Avoid this company, the lack of service is atrocious!