MTN is forcing me to pay for something I didn't want firstly and didn't use

MTN wants me to pay for a service that was suspended by them as I did not pay because I asked for cancellation last year October and still has not been done. They now telling me that as per their terms and conditions that the account should have been cancelled 30 days before the contract was to expire which I did request for and was not done now I have to pay for a service that I firstly didn't want any longer and didn't use due to the suspending the service