Let’s think this through for just a bit. Given that you’re no longer working there (or soon to be unemployed) it doesn’t hurt to wait a short while and consider your options. If you’re wanting to file a complaint out of anger or feeling taken advantage of think twice. Give it some time before taking action and ask yourself if it will be worth the energy and possible pitfalls of either suing or filing a complaint. You’re technically not allowed to be working because you need a B visa and a work permit. An O visa doesn’t automatically grant you the right to take on employment. So, maybe it’s better, as others have said, to just walk away. Maybe you decide to pursue this further. Ultimately the choice is yours but consider all angles before acting.