Bad Service MTN

My contract expired on the 20th of March 2021. I have been in contact with MTN since the 20th of Feb to get the contract cancelled and the number to migrate to prepaid. Several emails & phone calls later, the contract has not been cancelled. The Retention department at MTN is not even answering your call. Phone calls for up to 30 minutes two to three times a day. Why is this such a mission and I have another 2 contracts that needs to be cancelled in April and then migrate to prepaid.