Shoprite is careless with priciing items

I visited Shoprite yesterday and found several irregularities regarding pricing. With their frozen french fries there was no price to be seen, and there were two batches of fries 1 kg and 2,5 kg. I pointed this out to a shop assistant but she seemed to have little interest in doing something about it. Then I saw a section with my favourite ice cream, blueberry and vanilla, all marked at R 54. However, when I got to the till they rung up R 79. I said no thanks, this is an error and take back the ice cream. The cashier said she can't cancel it, so she had to call more senior staff. Then I had to wait quite a while for the other person to come, which is a considerable waste of a client's time. I've been buying at Shoprite recently because of good prices, but with such errors I need to rethink my situation. Prof W Richter.