Tools needs:
Flat bladed screw driver and new bulb from VW @ £2.70 each.
Time required: About 5 minutes, it is a very easy job to do!
To remove the rear light unit put a screw driver behind the unit and start to lever it out:
You should be able to see a metal spring clip and this is what is holding it in place, push this in with your screw driver while levering the unit out making sure to leave the metal surround in place as this keeps the shape of the headlining around the unit:
Here you can see the metal surround that the unit slots into, DO NOT remove this. You can simply pull the unit out and the wire can just be disconnected:
To get the bulb out locate the small black circle and use a flat bladed screw driver to turn it anti-clockwise about 1/4 of a turn and it will become loose:
It is abit tricky trying to get the bulb out as it does catch on the outside of the unit but it can be done! Try putting a screw driver underneath and gently levering it out, do not use too much force though or you will break the bulb! Although it probally wont matter because you will be replacing the bulb anyway...
Once out this is the bulb:
Now simply put your new bulb in and reverse the process to put the unit back in. Make sure when you put it back into the headlining that you insert the end WITHOUT the metal clip first, the end where the cable is goes in FIRST!
Hope this helps. I will be following this up with a How To change the bulbs for LEDs soon when I can find an LED that fits...