Had the same problem after some nice person knocked mine out when they reversed into me. As Don stated, there is a single screw nearest the wheel which the bumper is retained by. Even if you relocate the two elongated, which should just push back in and click, without the one nearest the wheel fixed, the bumper just pops out again after a while. My lug was broken off so the screw would not hold it for long, You can access it more easily if you remove the inner plastic wheel arch. I could not repair the broken lug, so I just "superglued" it back in place and it hasn't moved in six months! Cheaper the a replacement bumper :D