Mtn contract cancelations

I have been trying to cancel a contract with mtn that has expired in June. I have sent multiple emails to their customer services email address and Noone ever gets back to me. I have also attempted to call their helpline which I end up sitting on hold for more than an hour with no satisfaction time and time again. It's like they intentionally ignore the calls that go through the cancelations department. I managed to get through once before and the gentleman that answered my call promised me that hewoukd ensure that my contract was canceled and they continued to charge me for a line that is not in use. Mtn is a bunch of ******