Last week I bought a 2005 vw beetle convertible 1.9 Diesel, my first long journey on the motoway was a few days ago, around 20 miles into the journey driving around 70 miles per hour in 5th I dropped down to 4th and suddenly I lost half its power, I had to have my foot flat down on the accelerator and couldn't get higher then 50mph, the engine felt very sluggish, I turned round and returned home. Turned the engine off a few minutes later I turned it back on and all power was back on. It's a diesel 1.9 I wondered if you would be able to advise me on what you think could be the problem? I have spoken with the dealer I purchased it from and they said they would be happy to give it to the motoring garage they deal with and they will put it onto a diagnostic, but I did mention to them that no warning lights came on at all. I also wondered if I am within my rights to get the work done with a garage I know rather than use who they recommend (give the dealer the invoice) or whether that would affect my rights, also I feel unsafe to drive the vehicle so I wondered whether it's the dealers responsibility to pick up and drop off the car if i do use the garage they recommend to do the work? Thank you for your help