Daylight *******

I purchased items on special at westgate. Prawn meat, seafood mix and yoghurt. When I got to the till it showed the original price, then I had to walk back to the place to show the cashier the special price. I just got home only to find out the yoghurt was also charged at the original price. Why do you have specials if you dont update the prices? This is daylight *******. Which means many people pay for the original price thinking its on special.