Bad Service

I bought an item at Game in Eastgate, I checked my slip when I was outside the store and that's when I realized that I was overcharged. I went back to the store and told them & the supervisor said that they'll refund me the difference. I asked them about the CPA(Consumer Protection Act) what it says. I asked her if I'm not supposed to get this item for free and she said CPA doesn't apply at Game, it only applies at Pick Pay and I'm just surprised that how come this law applies to certain stores and not them and for the fact that they know that it applies at Pick Pay it means they are aware of this policy. They even said to one another, 'when you work in a shop that's when you become like this because you know too much'. I'm really not happy about their service because they even said to me that they're white customers are always overcharged but they've never demanded items for free and now I'm asking myself where does race fit into this equation?