Unacceptable and disgusting attitude

Yesterday my friend and I went to Woolworths Cresta mall, did a bit of shopping including the food market, we took cheese (x4) which was on the shelf where there was a special ad. Gouda or Cheddar (buy any two for R 95) when we got to the till we were told by a very nice friendly lady that the special was on the smaller cheese, we tried to explain that we took the cheese where there was a special sign ad, and that was the only cheese on the shelf. We then asked if we can speak to someone in charge, the lady came and did not even apologise for false advertising, she just said the special is only for a smaller size (400g), and she just asked if we are taking the smaller size cheese, and we said no because we took the cheese that was on the shelf where there was a "VISIBLE" special ad. I did not understand why she couldn't even apologise for their mistake, that was false adverti*****t, it is not the customers responsibility to compare the ad special to the size and check if it is the correct ad and whatever stock that is there is the correct one. The lady had an "I don't care"attitude. It was pathetic. The least she could have done is to apologise, what they did was wrong, was their mistake and ignorance. I am very disappointed.