On Saturday morning the seller helped me test the camera and find a workaround for the focus issue.
There was certainly an issue, specially with the left side focus area and we SET THE FOCUS POINT TO THE LEFT. Now I USE THE FOCUS POINT TO LOCK THE AREA I want to focus on and I am able to get sharp pics with this workaround.
I will just wait for Nikon to find out the reason for the issues and come up with a solution before doing anything further.
The Sigma zoom seems to work well with D800 and surprisingly the Sigma macro lens that did not work with the D200 is working better with the D800. No urgent need to update them - and no money =).