Overcharged on two items

The consumer protection act requires that a \retailer must not display any goods for sale without displaying to the consumer a price". That said however I have noticed a trend towards supermarkets displaying the wrong price when compared to the scanned price. The scanned price NEVER appears to be less than the marked price. Today is but an example of the problem. Two items where scanned at higher than the market price. For the one item it was conceded and the price adjusted for the other they refused to do so indicating that if I checked the barcode number I would find that the price was for the low fat version of the same product which was shelved far from where the price was displayed. Other than the barcode number there was no other way to determine that this was not the price of the item. The supervisor did not apologize for the 15 minute wait and the inconvenience and when I returned to the shelf to make my point I noticed all the barcodes had been removed. The small differences are often noted but ignored because the inconvenience isn't worth it but I have to question when 1 or 2 items are incorrectly priced in every trolley how much is P&P gaining a month/ year? """