MTN pathetic service

I have been trying to cancel an MTN cell number for over a year now. This is the most atrocious service I have ever encountered. I have sent about 10 emails, been to their offices and tried unsucessfully to contact the call centre telephonically. I have been cut off in the region of 50 times by the call centre. Apparently this is the ONLY way I can cancel the number, I still have not been helped.