Remove bumper; heat dent area from behind with heat gun (or hair dryer if you must) until other side is just too hot to touch; them push out dent with hammer handle or hand in asbestos gloves, suitabley shaped implement etc; cool immediately from behind with wet rags. Bumper plastic has a memory and will usually return to the original shape if heated and pushed back as described. Repair any small scratches with palstic bumper putty and respray as required.
Thank you Aussiblue.
Last time I tried to remove the bumper and it wasn't easy, half way I gave up. I may give another try.
Anyway, there is no cratch on the bumper (BA falcon bumper), will the paint stand the heat ?