1) Is it your insurance or their insurance that wants to total the car? If theirs then talk to your agent and see what he can find out.
2) There is a design flaw on the passenger airbag deployment of your series of cars. There should not be any reason that the dash breaks from the bag deployment. Maybe the top may rip open and the dash pad cover may need to be replaced, but it should not have done what it did. Even the 93 and 94 Nissan car with the "Mike Tyson Punch" airbag did not break the windshields. I would talk to GM and other owners whom have had this problem and go from there. That dash and windshield has added cost to fix that really should not in this case need be.