Closed tailgate this pm using internal handles as normal and the whole door card came away. Arrived home intending to get local dealer to sort but had a butchers and noticed that there are screw holes at the base of the handle aperture which look as though they have never been used. Looking at the white plastic 'receivers' in the tailgate structure sort of confirmed never been screwed (!) Lined up all the lugs and gave it a thump around all the edges and found a couple of self tappers of right size. Job's a good 'un.

Might be worth having a look at yours - mine lasted 6 months of closing before giving way.