Incorrect pricing at Clicks

I visited the clicks store in Newcastle Mall (KZN) on 19 Mar 2018. I purchased 3 items. At the till 2 of the 3 items rang up higher than the pricing g on the shelf. I had to get them to go check and they subsequently changed the automated pricing to the shelf pricing. When I questioned why the pricing was incorrect I was not given an answer and the cashier became offish and sullen. If 2 out of 3 products have the incorrect pricing then I can only imagine how many more customers who are not paying attention are getting overcharged. What's annoying is the unapologetic manner of the staff for the inconvenience and wasting my time.