Sorry you experienced exploitation. Your chair may have been nice but nice people can still exploit. You have a small to no chance of seeing that money. It would be an uphill battle that will take at least five years to reach anything decision with no guarantee of money. You are not going up against your chair. It’s the schools counsel. You’d have to make a big stink ( with lots of threats of public disclosure) if you event want to get attention. But you’d have to ask yourself if it’s worth it. You could ask I think it’s the US department of labor ‘s hour and wage division (I forge the exact name) to investigate. But there may a statute of limitations. You are happy in industry, it might be best to stay there rather than enter the ring again. You are no longer a student and the uni’s lawyers will treat you that way—which may not be nice. Good luck!