Insurance not paying because of prior damage

Had car accident. The other party's insurance(State Farm) has admit at fault. However they are not willing to pay anything after the estimation.
They said the prior damage on my rear bumper warrant the bumper to be replaced prior to the accident. I am only asking for the re-finishing of the bumper for the scratch caused by the accident, not replacing it. They say they can't re-finishing it without replacing it. Thus, no reimbursement at all. Is this reasonable? Do I have a case if I take this matter to small claim court?
I live in San Jose(Santa Clara County) California.

Answer:
You must be put back in the position you were before the accident. You had a painted bumper, that is what you get. If they have to replace the bumper to do that, then that is their fault.
Small claims could be an option for you.

Talk to a local attorney

Good Luck
http://www.auto-insurance-claim-advice.com/