Debit order not stopped and reversed

I have requested back in November last year for MTN to cancel my account. I have paid the settlement amount and sent you the proof of payment but they are still deducting money out of my account. I can not do any reversals or stop the debit order due to COVID-19.

I have phone FNB a few weeks ago to stop it on the system and to reverse all the money MTN has *******ly deducted from my account since I cancelled and paid the settlement amount from my bank account that I have with you. I believe I will have to close my account to resolve this whole issue.