I need some help diagnosing a problem with the second car, it's a 2008 1.4ltr diesel that has only done about 6,000 miles. Every time you go over 3,000rpm the engine keeps revving without any power going to the wheels - to get back power you have to drop down below 3,000rpm again. The car clearly shouldn't be doing this - not sure if it's related but at about 2,000rpm in 3rd and 4th the car gets a judder - like it's about to stall - it never does though. The reason I ask is the garage don't seem to know what it is even though they have acknowledged the problem.
Any help appreciated.