These guys sound dangerous. Hopefully NOT a Nissan Dealership. Find another shop or dealer which is able to correctly align the vehicle.
The X's are very, very, very sensitive to alignment spec's and variance from left to right. Since the caster setting will usually have the greatest effect on tracking other then tires, a dealer that knows his shit will set up a veh to have slightly less caster on the left side then the right (approx. 0.2' degrees) to give a slight drift to the left to compensate for road crown and what seems like most X's desire to go right.
Good luck.