Hi Guys update 13th March - Dealers still don't know what is wrong with the car but at least they now accept that there is a problem. This has taken me several phone calls to them, and taking the service manager out in the car to prove the fault to him.
Beleive it or not but after they have had the car for 2 full days, all they could come up with was that they wanted to take the engine and gearbox out of the car as they though that the problem was in the clutch to gearbox. And to top it off they wanted me to sign on the dotted line to pay for this, as they said abusive driving is not covered by the warranty. Naturally I went ballastic.
After having waited to talk to the service manager, for for what seemed like ages, and then taking hime on a test drive which proved that this fault had nothing to do with the clutch and gearbox. He has since agreed to get expert help from Nissan to get the possible causes and get back to book it in again to get it sorted.
Cheers - Quazar