MTN taking money that doesn't belong to them 168

I have been struggling with them to sort out my account since last year. Numerous visits to their store; phone calls to the helpline and several emails later and still no results. I wish I could cancel my contract with them. They have been deducting too much money from my account despite the fact that I have a voice recording wherein they confirmed my monthly payment. Does the ombudsman hold them accountable? That would be my last resort before asking for a court order.