The price i see is the price i get

I went to jet Highveld mall this morning(24/10/15) to buy a dress and the dress was R74 when i get to the till point Bawinile was assisting ,she told me that the special ended yesterday (23/10/15) yet the price on that dress was R74 .she told me it was a mistake , so i m asking who's mistake was it ? She told me that she understands.she called Bongi and she failed to assist me because she told me that she can't do a prices change on the system. So my question is that : wasn't i supposed to get that dress with the price i see? I think they need to go back to training because you can't fight with a customer over a prices that she/he see. That was bad service i got from them.