see the above for what i can see to be a common bumper fault, I attempted to fix mine today and i did so perfectly, only suggestion i would reccomend is get correct size rivets for the job
The bumper doesnt sit flush to the body and so it can look a tad unsightly,
now when you remove the bumper you have a black plastic part that the bumper "clips" into place on. This part is rivited to the wing, i removed the part by drilling the rivets out,
this plastic part is located here..
this replacent part i just riveted back into place and then replaced my bumper and now it sits flush again..
sorry for the bad how to and lack of pics,had the problem since i got the car and i know a few mates with the same problem now its something i thought i'd let some people know it can be fixed.
part no.s G1406523, G1406522. They were 5 euro each so about 3GBP i'd say.