Well, it's hard to determine the amount of damage to your vehicle without seeing it. Here are a few suggestions.
Get your insurace involved. Let them know what is going on and ask them how you should handel it.
You may also want to go to another shop to get a second opinion. Make sure you have all the facts correct. Would another shop repair it the way Liberty Mutual requests? If not, let your insurace company know about it. Ask them for suggestions.
Does anyone else have any suggestions?
Keep us udated on what happen. I'm interested to see what happens.