Cant make calls - MTN cant resolve!

Since 7 Dec 2020 I have been unable to make calls or send SMS's from my cell phone. I get a voice message saying "Service has been suspended". I can however received calls and SMS's. There have been multiple attempts to resolve with MTN. Reported to MTN Complaints Dept on 17 Dec 2020, and again on 19 Jan 2021. Then get an e-mail saying "MTN records indicate matter has been resolved"..........