I am assuming that your former employer is not a government agency and that you were not a member of a union that has an appeal process in its collective bargaining agreement (CBA). If my assumption is correct, then the employer doesn't have to offer an appeal process at all, and the appeal it offers can be set up in a nearly endless variety of ways. Since I don't know the details of your former employer's appeal process and what sort of arguments company officials might find compelling there's not anything I can tell you other than to be very familiar with the facts, know what you want to present well so you don't stumble too much in presenting your side of the matter, and be ready with any rebuttal you have concerning the reason the company told you was the reason for your termination.