Get an attourney FAST!!!! The insurance company is trying to rape your G/F. Don't sign anything!!! They should be paying all the bills after the first $500, not refusing to pay until she ponies up the deductable.
I hate crap like this. If they total the Cavalier, they won't be doing her a favor - in spite of the fact that its a crappy car. They'll pay trade-in or wholesale for the car, not what she owes. That means she'll be responsible for a couple of grand difference - unless she got "Gap insurance". Gap insurance will cover the difference.
By the way, don't tell her this stuff yet. It'll just upset her. Let her know that she has GOT to get a lawyer!! The insurance company will ruin her credit and whatever else they can if she lets them.
NOW IS THE TIME TO FIGHT!!!!!!!!!!!!