[Topmounter]

Definitely be professional and mature about it, gather the facts and present them. Make sure you are dealing with someone with the authority to solve the problem. If it starts to get out of hand at any point, escalate... escalate... escalate... don't get lured into a pi33ing match with some underling who is just trying to cover his arse. If you have a lawyer, then depending upon the initial discussion, it might be worth having him/her send a letter to the dealership on his letterhead summarizing the situation.