help!! Alfa insurance too bad.

My car was scratched one week ago and there's no doubt it was the other driver's fault. I then called that driver's insurance (Alfa) company. They let me take my car to do two estimates. I did. Bodyshop A asks about $50 more than bodyshop B, but I plan to fix my car at A because I don't need to wait too long. I gave Alfa both estimates as they requested and told them that I will fix my car at A bacause I don't need to wait. They said OK at that time. But today I received the check. They would only pay me the money that B estimated. I called and asked them if I have the right to choose bodyshop. They said: "Yes, but we only pay the minimun.You need pay the extra money if the bodyshop ask more than that." I think this is rediculous. It is their job to negotiate with the bodyshop if they think it asks too much. Why should I pay for the damage?

What should I do with Alfa? Does anyone know if there is some law that gives victims the right to choose bodyshop? Is there any place that I can complain?

Any help will be highly appreciated. Thanks a lot!!