FYI The cost of getting my high level brake light replaced at a VW bodyshop is just shy of £400
I am pursuing VW UK for goodwill (supported by the dealer) as I feel this is a stupid price to pay for changing a jumped up light bulb. The dealer agreed it was a stupid design and should have been a couple of screws from underneath but hey ho.
Mine doesn't seem to have any water in it but half the LED's are shot anyway. Maybe its so full of water I cant see it!
Will let you know how I get on.