Should my brother take this to court for retro pay?

My brother has been working for the piggly wiggly in our town since 1998. He's a little slow so he doesn't understand much. He's still there to this day and he is only making $7.65/hr. Now I think he should be making way more than that. He says that there is a guy there that works with him that started about 3 months ago and he is making 8 something, along with plenty other employees. I know that Im not crazy and I know that they are taking advantage of my brother. They are always calling him on his days off to come in to do things that they should be doing especially if they are working in the same area and he does not get paid cause he said that he doesnt clock in when he does that. I know that they are in the wrong and I need to figure out what steps do I need to take to make sure that my brother is treated fairly and given his proper earnings.