no promotion

I bought from musica in riverside mall at Nelspruit on Thursday, 15 October 2015 at 16:37:13. I want to buy the promotion of buy 3 cds for R99. when I go to pay at the till, the lady said that the items was not on the promotion.. however, she already removed the 3 for R99 labels. two of the items was less than the price on its label and two others was a lot more. now- I feel that the price advertised is the price that a customer must pay for the advertised and labelled item. I actually wants my money back for the overpriced products . I bought 9 cds that was on the promotion, but I have to pay R387.05.