Help understanding auto insurance settlement and if I need to seek legal help?

My 17 year old son was driving his 2003 Ford Explorer, when he was hit by another vehicle. My son was approaching a stop light and traveling between 3-5 mph....The vehicle that struck him was a company work vehicle. The work truck was pulling out of a parking lot when he hit my son. His estimated speed was also 3-5 mph. There were no injuries at all, and there was no medical treatment sought. This all happened on April 10th 2011. It was found that driver of the work truck was at fault for inattention. Honestly, this guy was super nice and walked my son through the process of calling police etc til I could get there....Now dealing with the Companies insurance carrier has been a headache!!!! here is the basic timeline....Explorer still drivable....Had to wait 10 days for police report....contacted Company that owned work truck, and they forwarded me to their insurance co....Was advised to seek several estimates, and fax them over....Faxed over estimates to adjuster. All estimates exceeded 5k....Stated she would have to contact an adjuster from local area to work this. Local adjuster came out. Estimated damages to be 3300.00. Insurance Company sent me check for 3300.00 and advised me when vehicle repaired, auto shop would need to work with adjuster on any additional repairs and costs. Explorer was in shop 30 days before finally being totaled. Local adjuster was horrible to work with, did not communicate with body shop, etc. I finally contacted the insurance company, and told them I refused to deal wither contracted adjuster etc. Now that the vehicle has been totaled, they don't want to pay what I think is fair. The insurance company wants to settle for $6928 plus $367 for taxes. Clean retail for the Explorer is $8100. This is for my area. I have been car shopping for 2 days straight. can't find anything comparable with the money they gave me etc. I have taken off work to deal with this etc, been going on for 2 months plus, and Iam worn out with it all...All I want is for my kid to be back in a safe reliable vehicle. The insurance company did provide a rental car. I had to drive it, my son had to take my car, my other son had bought our car from us, but can't get it yet, because the other needs it for work school etc....I am so frustrated with the ins ompany