Some D800s suffer from back focus (a large number of the earlier ones).
I would you suggest that you check your lens on a body that is known to begoods. If it is the camera it is preferable to exchange the camera - many who have tried to repair through Nikon have had less than satisfactory experience.
Thanks. I have tried all my lenses and they are all back focusing. How do you exchange a camera? I don't see Nikon doing that.