Cancelled Contract in June, MTN still deducting ********ly!

I terminated my MTN contract in June and requested MTN to migrate my 2 numbers to prepaid. I called in to obtain the penalty fees that I had to pay in order to terminate my contracts and paid R1682,49 on 23 June 2017. I also emailed proof of payment to them and only thereafter were my numbers migrated to prepaid. End of June MTN debit order went off, end of July MTN Debit Order went off again, and now another went off? I called numerous times to sort out this mess but nobody seems to able to sort out my problem. This is very bad/weak service from MTN. Are you now so frustrated losing a client that you want to make life hell for him by continuously deducting money from his account?