OK bit of an update, the stealer wants £380 ish to replace the brake light, this includes a new spoiler and painting etc.
A reputable bodyshop wants about £170 but they want to reuse the existing spoiler. When I pressed VW on why they wanted to replace the spoiler they were pretty vauge and said they needed to cut the old one off (which I knew) but couldn't offer any further explanation. The quote from the other bodyshop indicated they were going to cut it off and reattach.
Have you chaps who have had it done get new spoilers or the old ones reused?
I've emailed VW UK about this, I'm not happy at potentialy spending £400 becuase of a badly designed light bulb. They met the cost of window regs on mk4's that were out of warranty so I'm hoping they do the same for this.

If that fails I think I'll be in touch with some of the consumer mags, they'll love VW charging £400 for a (jumped up) light bulb