Overcharged at Pick N Pay

Went to Pick N Pay yesterday, purchased Ice Cream marked at R91.00 was charged R158.00, Yoghurt marked R32.00 paid R56.00. Had to go all the way back to get my money back. all they could say was "sorry" but did not change the price by the time I left. Come on Pick N Pay get someone to do their job properly. Very disappointed in Pick N Pay