Everyone at my temp job got a raise to $20 last month, and I should’ve too, but my job agency never told me nor gave me the increase until I called them to find out why I didn’t get an increase. And they won’t retroactively pay me back… is there anything I can do? Can I even sue?

Everyone got the raise automatically except me. Everyone I only got the increase after I called the agency a couple days ago, and they said I should’ve gotten it since at least last month but that they can’t do retroactive payment to make up for failing to increase my pay at the same time they increased everyone else’s. This is some bullshit. Is it grounds for a lawsuit against the agency? They always lowball me… The agency even had the audacity to tell me to send them an email so they “don’t forget” to give me the raise.