I have a 2012 2.5 Jetta SE and am due for my 40,000 miles service. The dealer quotes me $600 for the service of which $250 is for spark plug replacement. Do they change anything other than just the plugs like wires etc or is this just a total rip-off. I don't have much experience as a DIY, I've only changed oil and replaced brake rotors on my 1999 Audi A4. Is it hard to change spark plugs/could I do this and how many hours will it take? How much should a non-ripoff garage charge for plugs replacement?