Disappointing MTN

Good day . I had a contract with MTN which expired end of April . MTN did try to get me to renew the contract but I had refused with a reason that I didn’t need it anymore. I’ve tried for a countless number of occasions to call the call Center so that I can cancel it , but have not been able to get any help. They continue to debit my account even though the last time I spoke to them , I had made it clear that I do not need another contract. They are even debiting more than the amount I had initially signed up for when I took out the contract in 2019. I’ve visited 2 branches at malls trying to get this issue resolved but even at the branches, I’m told that I should call the call Center for cancellation of contracts. They even said that I’m not the only one to not receive help through the call Center, and that some people do try to call from the MTN branches but also just end up disappointed as there there is no response from call Center side, the phone just rings unanswered. I’m very disappointed with the kind of CUSTOMER service offered by MTN , and would greatly appreciate your assistance with regards to this matter.