MTN Customer Service Centre

MTN Customer Services, more the lack there of!! Have been trying to cancel a contract for a month now and have just received a bill charging me for another month. Phoned the Customer Service Centre and the lady disconnected the call!!! This is not service, it is an irritation. How do you cancel a contract if they disconnect your call??? Would it be too much to ask to have competent people in your call centres??? This is unacceptable.