Contract cancellation

I regret buying a phone with mtn on contract, their service is nonsense,when you go into the store for help they tell you to contact call center,when you contact call center,their employees are rude and don’t even know what their doing,I had to call for several months before they could cancel my contract which was due for cancellation but they kept on saying it’s canceled only to find out that they were still debting from my account,then now my number doesn’t receive or make calls,and all stuff is saying my number is working