How do you get through to Vodacom head office to get a major issue resolved????????????!!!!!! BEYOND UNHAPPY CLIENT

I really don't even know what to do anymore or who to contact to try and get somewhere with Vodacom... have posted already had 1 call a week ago assuring me someone from head office would call me and well surprise surprise I am still waiting and still have a phone that does not work and now is affecting my business! I am horrified at the lack of customer service and the ability for Vodacom to sort out their problems while I suffer - still paying for a contact and phone that I can do nothing with... I am at a loss for words!