Rear Running Light Replacement

Mine (German 2008 model) looks a bit different.
But in the trunk should be a small "door" opposite the light. Remove one and you should see wires and the back of the bulb sockets (maybe better use a flashlight).
If you rotate them a bit and pull them then you can remove them (limited by the wire).* Now you can pull the bulb out of the socket.
Maybe the print at the bulb will help you enough to buy a replacement.
(Better not touch the glass of the new one. The grease of the skin in combination with heat may reduce the lifetime. More important for headlights but who knows...)

* Removing the socket with the lights switched on spent new life to my dead bulb once. So maybe some movement of the socket or the wire Sam help in case of some bad contact.