Right now it's still your car and they have to get everything back to how it was prior to the accident so tell them you'll accept that offer if they pay to have everything you installed removed in your old car and reinstalled in your new one. If they won't budge then, rip everything out of your car, take what they'll give you and switch insurance companies. I fought and fought and fought with Progressive over a deer hit and after a year, they finally caved in and were going to pay for the repairs but later decided it was to expensive to repair and totaled it out. I definitely wasn't happy either but you have to take the best they will give you. Stand your ground but don't let them just sit on it either. Unfortunately, when they're the ones' paying out of pocket, they don't want to help anyone out but themselves.