Unhappy Customer who has been loyal to Vodacom for years

I am so disappointed in Vodacom shop at The Grove Mall in Pretoria. ‪A faulty phone on the store was sold to the customer last year August and even today the issues has not been resolved. Thabo, the technician is very rude to customers. Almost all the stuff in there are very rude, their attitude is not great at all, not sure where to report the issue because the store manager is like them. Vodacom customer care was contacted regarding the issue and mentioned that they need the technicians stuff number and this is something they cannot provide. The phone has been with them since September last year and it has been paid for. A communication was sent this year to say they did not find any problem with the device, however, the device will be on for few hours and screen will go off for few hours etc