Depending on your location and labor laws, you need to go after them for stolen/lost wages. “We thought you agreed” is no excuse for wage theft and if thats not in writing and you have the time sheets for it, you may have a case if you have records.

If its in MA (just a guess because its a higher-ed job), their wage theft laws have teeth to the point I would have a new job lined up while you work with your lawyer.