WiFi Calling still not working

Still waiting for Tech Support to get back to me. Wi-Fi calling not working since contract renewal over a month ago. Network engineer was here and was able to make a Wi-Fi call on his Vodacom phone, so problem is not with my ISP/Wi-Fi service. Live & work in an area without South African mobile signal so unable to make or receive calls unless using Wi-Fi Calling, which no longer works on the Cell C network. Have numerous. Have numerous Ref.No's from Customer Services, but issue never gets resolved.