I’d be going to DOL on non-payment for work performed issues. Try looking up Ledbetter Fair Pay Act.
And next time you want to raise issues on pay hours missing, email - even if it’s just to “memorialize our phone conversation on X date, time, when I raised pay discrepancy you advised - here’s my supporting timesheet provided to HR for X number of hours while me pay statement is showing y number of hours. Please provide contract/timekeeping SOP whatever saying employees need to work for Z number of hours for free as I’d love to consult with Department of Labor on forced unpaid work hours”.
Email gives you timeline, and often serves as the starting point (for example EEO issues which you could potentially use -have 45 days time limit from the day the incident happens or you’re made aware- being an immigrant from X country, employer retaliated against me by forcing me to forfeit worked hours thus reducing my salary by X percent over the course of X months in contravention to hiring contract signed on z date) …