I've done this on my head lights and Fogs, takes a couple of times to get it right, but now is no problem what so ever.
You'll have to take your headlamps out. theres 3 or 4 nuts holding them in (you have to undo the plastic wheel arch to get to 2 of them)
Also when you take them out, you will see a couple of flaps on the back, pop these open with a knife, rinse out and dry the foam thats inside.
Or better still get them changed if the cars in warranty