If you were not fired because of anything that is protected by the law, you have no recourse. You are entitled to your earned vacation, and you should ask for it in writing. You are also entitled to a copy of your personnel file and a statement as to why you were terminated. The two weeks severance was not required by law, so they could have paid you anything they wanted, or nothing at all. The certificates are yours. and they should return them. The only issues is wether you were truly fired for making complaints about safety.
Answered on Sep 11th, 2011 at 2:36 PM