Wrong price displayed

I went to clicks La lucia yo but a mouth wash. They put on the wrong price stick when I went to pay they told me the price of the mouth wash I'm looking for is not displayed the one that's displayed is a price of something different. My question is why is it my problem that they have a different price displayed that's false advertising. The manager by the name of Zinhle Bongwe just looked at me and said well that's what written and it's wrong. But the price of what I want is different.