MTN's faulty debit order system causes threat to personal safety

I switched from Standard bank to Discovery bank 6-months ago , transferred all my debit orders, notified MTN and received confirmation that everything was in place. Since then, every month MTN fails to deduct my debit order and then cuts off my phone due to non-payment, with no warning. I had a breakdown on the side of the road and no cellphone connectivity, which could have turned very ugly.

I went in to MTN Tableview , signed mandates and they confirmed everything was sorted on their side and I got cut off again at month end. I had a clear credit record but now have a default showing for non-payment because of their incompetence.

I've had none of these issues with other providers on debit orders. The attitude of MTN call centre and in-store staff is terrible , no apologies and promising to call me back with resolution and failing to do so.

How is it possible that they can lock you into a contract yet treat you so badly and get you listed on a credit bureau when it's their fault. No one seems to be able to help, I've tried escalating but no one calls me back. What recourse do I have against them ?