Overcharging

My Husband bought a You magazine today from Spar Mandeni. I look at the till slip and saw that it cost R44. I could not believe my eyes. As on the You book state's Rsa R32. They overcharged us by R12. I phoned Spar Mandeni to complain about the overcharging. The manager said that they would refund me the R12. Which they did. I asked him, why are they overcharging us customers. He said that the pricing was done by head office and he could not do anything about it. When I got home I phone customer care department of Spar KZN, and spoke to a lady there. I told her what happened and told her what the manager had said. She in turn told me that the pricing was done at each individual shop as they were individual owed, and the owner do the pricing. I told her I think that it was ********* to charge R12 more, then the book was mark. She told me that they were not breaking any law by doing that. I would appreciate it, if this practice could be stopped.