Time wait for no man

Pick n Pay Tramshed always keeps outdated prices on their shelves, I have noticed in my last three transactions that the items i bought were out by R1.00 each....but today was extreme...Red Bull Energy Drink 355ml shelf price was R21.99 but I was charged R25.99....I noticed after the transaction was concluded and went back to the cashier to correct the price.....help was recieved but waisted my precious time for a refund of R4.00....unnecessary delay.