Progressive Insurance Progressive refused to pay for damage done to my car by their client Phoenix Arizona

My car was rear-ended on the freeway by a party insured by Progressive.  My car made a terrible hammering noise as soon as I began to pull off the roadway.  The cause of the noise turned out to be caused by broken motor mounts.  Progressive paid to repair cosmetic damage but would not replace the motor mounts.  Their reason was the car was to old.  While the mounts were old they were not broken until the accident.  Now I am stuck with a sizeable repair bill for a problem that did not exist before the accident.