Rejected Refund

Ref:*** PATHETIC! MTN are owing me over R2000. The retention department has an issue with a cancellation fee of R200 which was paid in store and as yet to be actioned on my account. I phoned them on 19October where they ensured me that I will be refunded in 48hours. Received sms with above mentioned reference saying that I still owe the cancellation fee and refund rejected! *** REALLY? Why does MTN get away with unresolved issues like these? Where can I report them? Ombudsman?