Its nearly a pity that you were not in the car because when the other party is in the complete wrong insurance tend to get everything sorted out as quickly as possible for fear of personal injury claim.

I'd imaging you would pay a premium for a red car so you should look for cars advertised at higher prices and make links to your own car as to how it's similar and you would have to spend that much money to get the same car again. You should also insist on a rent a car until you get your agreed value. DO NOT give the rental car back until your agreed value is met, be as stubborn with them as possible. Remember it's your car and they have to agree a price with you to buy it.

If you broke something in a shop you would have to buy it for the marked price.