Hi there,
I'm sure you have solved the problem by now, but I too encountered this very problem and couldn't find the answer anywhere... for days, then I found this - THE ANSWER TO YOUR QUESTION.... so here it is for anyone else with the problem!!!
Open the boot
Undo the first retaining nut which secures the light cluster - it's a black plastic nut which has lugs on so that you can unscrew it by hand.
Using a screwdriver, remove the ventilation panel on the side of the boot just behind the offending brake light
Reach into the hole, and you will find the other light cluster retaining nut - unscrew it.
Pull the light cluster off the back of the car
Disconnect the wiring loom connector to free up the cluster
Squeeze/bend the retaining clips, and remove the cluster backplate
Remove and replace the offending bulb - it's a bayonet fitting.
Reassembly is the reverse of disassembly
Damian xxxx, September 2006
