You live in St. Louis and your state has a lemon law that only covers new cars, unlike say California whose law covers, more or less, all consumer goods. The AG, unless you have evidence of fraud, will just refer you to the better business bureau (who will take your complaint and forward it to Nikon requesting a response). In my experience companies like Nikon don't care about the BBB.
My advice is to use social media to your advantage. Idle threats over the telephone are private and really don't concern large companies with in house lawyers. Try posting to NikonUSA's twitter and Facebook pages. Try something like asking if they have an ombudsman (secret: they don't but play dumb) because you are finding it impossible to deal with your regional service depot who now has your brand new D800 for the 4th time. It may be enough to get someone with fresh eyes to look at it.
I used a similar technique to get another large company to expedite an exchange of goods that were DOD during the x-mas season. Their delivery/customer service department basically told me to be patient (as they were busy filling new orders, hey they already had my money) but a suggestion on their twitter account that delivery was insanely slow, gave them enough concern to get it out so that the public was assured that orders would be filled in time for Christmas. They didn't want that type of attention.
Good luck. I would note that the inconsistency of AF is odd, normally bodies that front focus do so more or less with all lenses. I am trying to figure out how your 105 could be dead on while your other lenses are badly front focusing and all I can think of is that the 105 is a bad back focuser.