Contract cancelation

Mtn has the worst service ever. A month ago I called in to cancel my one contract I have with them and today when I phone mtn they say the contract that I am canceling has been exstended with out my knowledge.

That is not acceptable I am not going to pay for that contract anymore and I am going to change my network provider when my phone contract is finished. I want an answer from MTN on how they are going to reverse their problem that they have created.