what are our bumper covers made from?

solteroblues

I've tried googling it and all I can find are parts for sale. so my NISMO conversion bumper was in the body shop getting painted, and they called me to tell me that after they put the sealer/primer on it, they found a crack. He said he didn't normally like to repair those plastic bumpers, and for me to call who I bought it from and see if they'd exchange it. Of course they told me that they couldn't do anything now that it's been painted. They also told me that the shop should be able to repair a urethane bumper like that no problem. So researching a little bit, I found a site that talked about urethane bumpers being the kind like you'd find on an old Cadillac or something.

What are my options here, other than just telling the shop they have to replace it at their cost? Is it made from urethane? Can it be repaired?