Just thought I'd comment and say a big thanks for this post, having suffered with a similar story.... MK5 GTI, just out of warranty (2month) and the rear high level LED went pop due to water ingress!
To cut a long story short, VW customer services would offer 30% discount on the £415 repair bill
(based on age of car, mileage, servicing history etc), which I politely declined.
Next day, purchased the parts direct from VW and following instruction posted here, completed a repair in 20 mins as suggested.
Not bad considering the £380ish saving and minimal effort!!
Any one else suffering from the same- give it a go (unless in warranty- although you risk a new sprayed spoiler being attached)
Cheers!!!