This relates to the most popular hatchback model.
- Open the boot.
- On the edge of the boot opening, next to the rear lamp cluster, there is a round plastic cap.
- Carefully prise out this cap, and this exposes the bolt holding the lamp cluster to the car.
- Unscrew the bolt, then carefully lift the lamp unit free of the car body.
- Remove the brake/tail lamp bulb holder from the back of the lamp unit, replace the bulb, put the bulb holder back in place in the lamp unit.
- Replace the lamp unit in position, re-fit the bolt, then refit the round plastic cover.
Heres a video tutorial off the process. Its in French, but still useful!