P.F.
Don't ask the repair guy. I know that sounds ridiculous, since they should know what to do. We had a Nissan when we lived in CA and found that one dealership would say one thing and another dealership would say another.
Call Nissan USA. I just looked it up and here is the phone number 800-647-7261. They are in Tennessee. It is their consumer affairs department. Let them know what is going on. Let them know what the dealer is telling you. There should be no reason why they cannot fix this problem, especially since it is under warranty. This is a true safety hazard. They certainly do not want a lawsuit on their hands.
Good luck and let us know what happens!