Tsogo Sun gift card

I have a Tsogo Sun gift card that can be used at any Tsogo Sun restaurant. Every time we go to a restaurant at Silverstar that is part of Tsogo Sun, tell them we will be using gift card, get the same response every time, we don't know about this card and don't accept it. This is quite embarrassing and frustrating. We have the same problem every time. It takes up to half an hour to get our bill sorted out. We then went to Billy G's at Silverstar, they told us we do not accept this card and cannot be redeemed here, we politely told them that they are a Tsogo Sun restaurant and need to sort it out. This restaurant is an absolutely disgusting. We got there at around 2pm! The buffet was pathetic, before we went there checked website out, menu on website was very different to what was being served. When we asked about the soda that was bottomless as advertised on web, where told that discontinued a year ago. The restaurant itself was a disgrace. Empty tables with dirty dishes, floor full of dirty serviettes lying around. Our dishes remained on our table till we finished all our dishes. I sent a complaint to Tsogo Sun and until today have not had a response.