UKPassats

I've been told by my mechanic that my 2.0 2007 Passat has an injector that isnt working properly. I know nothing about modern mechanics at all so have to rely on others (even though I used to be able to take the engine out of my Beetle in 30 minutes with a plank of wood).

I understand that a new unit is about £450 plus labour!!!

Is it really possible for a unit 3 years old to "go faulty"? The car only has 35K miles.

What alternatives have I got?

Thanks for your help