Vodacom unable to fix problem on their side

On 1 of my contract phones I can only receive calls and cannot make calls. Pay R175/month for airtime that I cannot use. Phoned the call centre from my other phone and spend about 40 minutes with the Vodacom representative to try and solve my problem. Was informed that all seems to be fine on their side. The lady informed me to give it 24 hours and it should be fixed. Result? 24 hours later still the same. Today, 2019/12/12, I went to the Vodashop in Greenacres and the lady there also checked on the system and could not assist. She requested that I phone the Call Centre again which I did. Again spending 30 minutes + the lady eventually informed me to do a sim swop which I did. Left simcard out of phone for the required period, put it in the phone...problem still the same!! I basically wasted my money to do a sim swop since the problem is NOT solved. I honestly don't feel like spending another hour on the phone with Vodacom in order for them to fix this. What must I do next?