Staff not aware of advertised specials

I went to the Gateway Centurion branch to purchase Black Tie wine that was advertised on their website 3 for R90. I was charged R100. I complained and requested for the supervisor. The supervisor insisted that the price is correct, refusing to check, going as far as telling me that she loads the specials. I requested to see the manager and was taken to Dolly. She went on to spin the same story as the supervisor. All I was requesting was that she check on her website. When she realised that I will not relent, she eventually went onto her computer. After a good few minutes, she showed me an advert that was not from their website, but a newspaper or directory. I insisted that she check on her website. Eventually I took the mouse and showed her the website and the advert. She calls a person I think a Mr. Meiring. After a protracted conversation, she tells me that it is a advert for Cape Town. I told her that I don't care because the advert is on her website. She eventually decided to give me the wine at R90, all this after a good 20 minutes. This all because staff don't trust customers and promptly check the facts. I'm going to definitely change stores.