If you look at the trim behind the lamp in the boot, the trim is held in place with little black buttons. get a blunt knife under the button and lever up. This will release and can be pulled out. Once you have done one, you will see how easy they are to remove.
The lump of plastc the boot latches into has three buttons.
The plastic trim below pulls off if you pull it towards the front of car.
The plastic behind lamp has three buttons, also remove those.
Then operate hood as though to open and stow until the boot lifts. This gives easier access to remove the the plastic behind the lamp. Wiggle out of place. Now close roof.
Open boot.
Next disconnect the wire connector, then remove the three nuts hold lamp in place. From outside lift the lamp out from the sharp corner as the rounded part is located by two lugs into body work.
If you are getting water into the corners check that the seal from the lamps is fitted properly.
In fact if you remove lamp you may better see how the seal is supposed to fit.
If you are getting water in the lamp, unclip the rear of lamp, you will see a rubber seal. If wet dry out and Evostick it back in place, then Evostick the clip part back to lamp. This has cured my water in lamp housing.
When refitting just make sure the oval seals on lamp housing are fitted correctly otherwise you will get water into the boot corners.
Also make sure the rubber seal around boot is firmly pushed down in place.
