my bumper was cracked, not broken just tiny cracks in the paintwork that had peeled off over time and left the black plastic showing so first was to key the plastic up and surrounding paintwork, repair using a suitable filler,rub the filled area level with bumper, flat it down using a fine grade 1200 wet and dry abrasive paper(aldi toilet roll will also do the trick
),prime using plastic primer,key up again then followed by plenty of filler primer, wet flat the primer untill its really smooth then apply a base coat(bought from ebay) let each coat dry, give it 3 coats, then leave to dry, after its dry coat it in halfords clear laquer, it helps if you have had the can in a bowl of hot water to give the laquer a tempurature to flow better, i also used the daughters hairdryer on the bumper to help it dry as it was cold when i sprayed it, leave the finished job for at least 3 days then wetflat (1800 grade) untill smooth but not too much that you`lle be through the laquer followed by much t cut and elbow power or a polishing mop and compound
, by the way, take the bumper off or mask lights etc. cost of repair £22