Had enough of MTN's NO service

I phoned 3 times and spend 50 minutes or more on the phone each time since 30 October 2020 to cancel a contract that expired. Still today it has not been canceled and they are still billing me for this account. I have end messages, all respond I get Every time is sorry for the inconvenience, I sm escalting your requests to retention who will be in contact with you... Or the last one saus, I referef it to management... But still no one is contacting me and thdy are still billing me. I am not paying a cent on this contract for anything that was billed from30 October.