Putrid service from MTN

I tried to call MTN on 1 October 2021 to cancel my contract as I won't be upgrading and to make my sim prepaid. I could not get through to them for over a week. I then messaged them on FB via messenger to change my sim to prepaid on 18 October 2021. Two tickets has been logged and I've been billed for not canceling my contract when I've been trying to do this for 6 weeks! MTN then had a nerve to tell me to call their call centre to cancel. I expect to have this resolved and refunded! When I told the consultant it better be changed to prepaid and I better not be billed they were quick to apologize and then bill me! My second contract is due for upgrade and I was going to upgrade with the black Friday special but I'm tired of MTNs bull**** service! I will be making all my contracts prepaid.