false advertising

on the cover page of the rising sun read one day special Liqui fruit 1.5 L R17,99 on the 27th April 2015. When I went to the store on that day. I was told it is R24,99. When I queried this with the workers at the aisles I was told there was no such advert. I also noticed at the till was many of the above mentioned left behind. I am very disappointed.