I have just replaced both of my plastic sills (side member trim), make sure you buy the cover trim also for the top as the chances of not breaking it are nil! I have an 03 car so it is 8 years old, the plastic is brittle so rather than fanny about with it you are better to just rip it off. I spent ages trying to remove them in one piece but lug after lug they cracked off. To remove them I used a wooden spatula, sounds daft but protects the paintwork!