Had a fiddle with it but i dont think the seat plastics have anything to do with the lock mechanisum, well its not realeasing the seat anyway. Ive managed to move the seat unit and bend the undertray down enough to see inside but cant find the rear light mounting bolts and tbh i dont think unbolting them is going to help as i still wont be able to remove the light due to the undertray being in the way.I think i'll just cut my loses and source a new undertray, then cut though this one and sort the lock out.