You can't have it both ways: you can remain anonymous *or* you can file a complaint, but you can't anonymously file a complaint for not being paid overtime, since the investigation will necessarily point you out: that is, if the department of labor accepts and looks into your complaint, they will have to look into *your* payroll and timesheet information and will instruct the company to pay *you*. There can't be an investigation into whether you are paid correctly without your name coming up.