Welcome to retail management. Been there, done that. Your mistake was working off the clock in the first place, OTOH if you don't then any chance of further promotion is gone and they'll look to replace you with someone who will. K-Mart still owes me a day off with pay from 1982. Normally when you are in "management" you are classified as an "exempt" employee, meaning exempt from overtime, minimum wage, etc., essentially a glorified stockboy who works for cheap, if not free.
See if the purported AZ rep here can help you. If not, take them to court. You can go to a local magistrate and file yourself, you won't need a lawyer. My wife did that a couple years ago with her former employer who still owed her several hundred dollars in travel expenses after she quit. Her dept. director essentially told her to kiss off and he wasn't reimbursing her because he didn't want to (you can see one reason why she quit). She had the all documentation (she IS an accountant) and the day before her court date we get a call from an executive VP at the corporate office, asking what this is all about. She explains, he asks if we could postpone the court date, and she had a check via FedEx the next day. Don't know if her former director got into trouble about it, but we hope so.
Ideally you should try to get AZ into the position that paying you is cheaper for them than paying lawyers.