Struggling to cancel One2One contract since 2019

I cancelled my One2One contract in October 2019,but Im still on the contract. Every time I phone to complain they say its Technical problems from MTN self,but I have visited MTN directly and they tell me that they don't know of any technical issues. I want to be off this contract ASAP. Bad customer service,as I e mailed them too,but no one ever phones back.