Bad Service received from MTN

I really had a bad experience with my contract with MTN after having a contract with them for over 20 years. My contract was extended without my approval and when I tried to understand how was this the case, I was tossed from pillar to post until I decided to cancel the contract. I was told to write a written notice giving them 30 days which I did. Instead of processing request for my cancellation, I was told rudely I should call the call center which I did. I have made more than 10 calls with no proper resolution of my problem.