Looking to replace the rear LED brake light which is sits on top of rear window - can anyone confirm how you go about doing this  - thanks 

Hello Dennis,

Thanks for joining and posting your request. 
I don’t know how the R8 high level brake light is held in place, but Incase it helps, with the  A3 you have to ease back/remove the plastic trim in the interior behind the light unit. You may then find a number of sprung white tapered fixings - each of which need to be compressed with a long nose pliers to release them- the springs will ensure they remain released. The unit can then be removed and replaced. Watch the rubber gasket. 
Using Chinese ones ?? How long will the LEDs last? 
Might be worth looking on You Tube to see if there is a listed procedure for the R8. 
Kind regards,

Gareth.