You will likely lose playing hardball with quotes on body shop estimates. Just use their shop and they will guarantee the work and if its not right they will fix it. Most attorneys dont take the coll portion without their being some type of Bodily injury involved as well because their is not enough money to be made. They will more than likely tell you to pay the difference or they will talk to your shop about their estimate and see why they are so different, try to negotiate it and when that doesnt work they will tell you they arent paying that. Its normally much cheaper for the ins company to use their shops because they already have rates established on parts and labor with those shops which i have seen vary by as much as $30 an hour. Its your call but you wont win. When all else fails, they will go by mitchells or whatever estimating software they use to the letter.