Dart is totalled.. now what ?

Been there, done that. Get a lawyer to write them a letter detailing your justification for the higher settlement and threaten a lawsuit if they don't pay you what it's worth. It was THEIR driver that caused this situation, not you. The lawyer will cost you about $150, well worth it, and it will demonstrate to them that you are serious. Then they will weigh the cost of what you want vs the time and expense of fighting you in small claims court and will make you a higher offer.
Being in the insurance business I can tell you, the folks in the 'total loss' department are vicious, and they are bonused to minimize costs in situations like this. They don't care about what is right, they only care about paying you as little as possible on a totaled car. You will get nothing from them unless they know you are going to be a bull dog. They will be very convincing in their arguments that your car is only worth 2800, but I assure you, if it's worth more, a legal threat (from a lawyer) will get more money for you.