Checkers Allens nek charges higher than what's advertised

Checkers Allens nek has multiple products that you get charged a higher price for than what is displayed on the shelf. I had to indicate the price of 2 items to them which I was charged R20 more for each and R25 more than the advertised price of the toothpaste which I didn't pick up at the store. After indicating to the cashier the price is different on the shelf.