Open Question: Insurance Claim Problem?

Ok so they hit and run my husbands truck and well the guy who hit the truck had insurance. We filed a claim,adjuster came out to take picture and look at the truck. Now they sent my husband a check to fix it which is $2500. We found someone that can fix it for $400 and we wanted to keep the rest of the money for ourselves. Now the insurance company is calling us for a quote on how much the