The only way you will win when you get this kind of brick wall is to lawyer up. Once this thing starts rolling they'll settle to prevent a drawn out battle. That said you'd have to get a lot to pay for the lawyer, so it's important to find a firm that's willing to take this on at no cost if you lose. I hear about that all the time, never actually employed a lawyer other then for a PoA...so I really don't know how that free retainer stuff works.