Expect nothing, the term 'main dealer' seems to just be a lisence to print money. My other half has a tdi passat, had it about 4 years.
Developed a turbo fault, losing boost in 4th gear. Brought it to the local main dealer, 250 quid later they diagnosed a sensor fault, sensor was about 25 quid. Robbery if you ask me.
Gets better though, developed a misfire at idle, did a bit of research and discovered it eas a wiring fault, back to MD, 250 quid to put it on the computer again, about 40 quid for the part i told them it needed.
Then she brought it back again for another turbo problem without telling me, I went and collected it....... £400, not fixed told me turbo lag was a cat fault, wanted me to pay about 900 for a new one......................
Brought it to a new mate of mine with computer diagnostic kit...... boost solenoid, 50 quid, 10 mins........................FIXED
I reported them to VW but surprise surprise no reply.
The profit in the car industry is now in all the electronic crap, computer systems and spare parts used by MAIN DEALERS surprise.
Even funnier is that a neighbour of mine got fired out of the same main dealer because he changed the back axel bushings in someones car and forgot to reattach it on one side!! He was atrainee at the time and no one senior ever checked his work...................
About all there is to be said about main dealers..... Find a good independant mechanic that knows the make and never go back.
Or do what i do for myself and now her too and only ever buy cars etc that you can fix yourself because they aren't full of sensords and electrics