Hyundai corporate

Basically my cars engine have failed and the corporate knows that this particular engine have problems with all the cars that has it, and i have took my car to Hyundai dealership mechanic and they have requested a new engine and the request was denied because of lack maintenance record.
What i want is a well written letter to send to corporate about the issue. If my case of an interest to a paralegal we will schedule a call and i will provide more details about the case