Need For Speed Heat Performance Part bug

Hello EA support team. I have run into a bug that only applies to one specific part in the game, and that is the gearbox. I am unable to acquire the Ultimate, or the Ultimate+ part for the gearbox. I have won many high heat races, restarted my console, unplugged my console, and restarted my game, and yet, this but will not be resolved. I am currently playing on Xbox, and do not know the error code, or how to obtain it. I would really appreciate some help on this matter. Thank you very much.