disco 6 auto transmission
 

hello
new to this forum
I bought a 2010 disco a few months ago and I have been having an annoying problem with the transmission.
Taken it back three times and its still the same.
The problem is on occasion it will roll back after stopping at a road junction. When I let the footbrake off I can tell its not in drive and it will roll back for a second then lurch forward. The garage insists its the gear selection lever switch that needs adjusting but they had done it three times.
I am a retired mechanical engineer worked on fork lift trucks for ages but never worked on cars and to me it seems to be a brake / transmission overlap issue
if it was a lift truck we would call it an inching problem.
The question is when the foot brake is applied while in drive dose the brake lower the clutch lock up pressure thus disconnecting the transmission until the brake is released or is there some other type of brake interlock fitted.

Check your transmission fluid.
The transmission slipping like that was common for a friend of mine's Rover... right up until he melted a clutch because the fluid was so low.