I leased a new Audi A6 Avant 2.0TDI Multitronic from my local dealership in March 2010 under a personal lease. Two weeks ago I noticed that the gearbox was slipping between gears (like riding the clutch on a manual) and it then started to stall on starting the car. It would also stall when going between D and R, and vice versa. The dealership now have the car and called yesterday to say that the gearbox has suffered a fatal failure and needs to be replaced. They will do this under warranty and whilst they have my car (due back 3 Sept) I can use an Audi relief car (A4 2.0 TDI). Is it completely reasonable for me to expect them to replace the gearbox under warranty and hope everything else is ok, or would I be entitled to a replacement car?