Poor service from AirMobile/Afrihost

I have migrated from MTN to AirMobile during May 2025 where I now have a package with data and airtime. I do get a monthly airtime allocation that I can't use. When I try to dial any number (using the allocated airtime) I immediately get a message "Call failed". I have engaged AirMobile more than 2 weeks ago and have interacted with 5 different people. Everyone so far has indicated that they are investigating it, however nobody comes forward with a proposed solution and a course of action.