Opel ASTRA Owner's Manual page 218

216 Vehicle care
2. Rotate bulb socket anticlockwise
to disengage and withdraw from
the reflector housing.
3. Remove the bulb from the socket
by turning anticlockwise.
4. Replace and insert new bulb into
socket by turning clockwise.
5. Insert the bulb socket into the
reflector housing and turn
clockwise.
6. Fit the cap and rotate clockwise.
4-door notchback
1. Release both caps with a
screwdriver at the marked area.
2. Unscrew both screws and remove
light assembly from the bumper.
3. Disengage the bulb socket from
the reflector housing by pressing
both retaining lugs.