Sorry to hear about your experience. I'm in a same sort of boat with my camera - I've sent it in for the second time, provided them with sample images and they replied to me that "it's within Nikon standards".
I think I will explore every way I can find and complain to every Nikon office I can reach as well as post as much details on this everywhere I can.
I believe that Nikon proves itself as a horrible customer service company and that they should suffer the consequences. This is not acceptable for a $3000 unit which does not operate properly.
I will follow your story as I would really want to see how it's taken care of in the US. I live in Canada.