I found two rubber discs that I thought were holding the lining in at the back of the arch, they wouldnt pull or twist to release, are there screws in a less obvious place that will release the whole lot (rubber bits included?)
There are screws at the top and bottom of the arch. However, you do need to remove the 'rubber discs'. Try to gently prize them out with a screwdriver. Sometimes you just have to yank them. On occasion they will come out intact and go back in fine but they may get damaged slightly - not the end of the world, though.
I had the wheel arch liners off my old 98 Megane loads. All the holding disc things got damaged and I lost a couple but the liner stayed on OK.