Incorrect pricing

Bought some goodies this morning @ Clicks Parkview PTA and after paying I realized that the price on the toothpaste was not the same as advertised on the shelf. To my disbelief I found that 4 of the 7 items were prices incorrectly. Management just said that the prices go up on Mondays and it was not supposed to be up today. My question is - if you take a R1 here and R3 there for everyone you can just benefit! Shockingly however is the amount that the prices increase - toothpaste for kids were R13.99, billed at R16.99. Wafersticks @ R19.99 billed at R22.99. Pantyliners from R28.59 to R29.99 and the toothpaste from R23.99 to R24.99. The principal stands that now the customer has to endure the time and effort to set this straight and then the manager makes a mistake and has to do it all over again.