Robbing people

I went to checkars to buy a few things for the house. At the back where the eggs is, is a big paper stating that 3 × 18 eggs = R100!!! When I got to the till the lady told me that the eggs is not the price they said at the back, they packed the wrong eggs there I called the manager guess her response, sorry the special eggs had been sold out!!!! I can understand that but why put a big sign up stating the eggs is R100 for 3 if it is the wrong ones!!!!! Is that your way to try and rob people hoping that they won't see the real price at the tills ????? I am really disappointed in Checkars. If I can give any person advice check your till slips everytime cause they will advertise things for say R20 and you will pay R50 at the tills, cause they know most people just pay and go without checking their slips!!!