Holy jeez. I'm so sorry, first of all. That sounds awful.
I suggest following they steps they offered, for one reason: if their warranty department and the post office won't assist you, then you can say "I did that." With customer service things like this, my experience is that escalating (politely, of course) and asking to speak to supervisors can go a long way. It may not resolve it, but it makes it more likely; polite persistence pays off (along with awesome alliteration, apparently).