what car bumper? if nothing major can DIY like Danz say...i cut my own front bumper so can fit my driving lights...n looks like original oni...
if need to do some fiberglassing to round of the cut...actualy oso can DIY. just buy the fiberglass strips/sheet n the resin n just form yrself...the mould can use hard foam to form...but if not sure better send to bodykit shops that know how to do fiberglassing...