Cancel your imaginary contract with me, with immediate effect! Stop Debiting my account.

I have just about had it with Telkom. I cancelled my contract (which was already on a month to month) in December. Every month without fail, my account gets debited. I have to go into the bank every month to reverse this nonsense, because, I refuse to pay for services not utilized! The people in the shops can't assist and log calls continuously. I have references for days, but no positive outcome. This is ridiculous. Then they have the audacity to send me account suspension notices. I don't care, I don't make use of your services. The bank can't even cancel the debit order because they have mastered the reference changing game.