According to the other string, the main stealer said that the wing had to come off for access. You may be able to release the catches by concocting something to get through the grille slats in order to release the latches. Maybe the AA or RAC could help if you are a member. You could try removing the bottom two self tapping screws which help secure the grille to see if you can "Spring" it forward for a bit more access.
As I previously wrote the cable is part no. ALR 6989 (Genuine part) and Rimmer Bros. are quoting £14.51 incl. V.A.T.
Ther are two latches with a cable to each-try giving the release lever a good pull-what have you got to lose??????