your insurance company will give the value based on parkers price guide.
you can check the value on parkers website, but its going to be way lower than any figure you'd accept, so be prepared for some arguing.
personally, id encourage them to repair the car. They wont be able to source a grill, so you'll have to find a used one, but a 71k moon grey plus is a nice car, and there isn't many about.
alternatively, see if they'll offer a buy back option, where they write it off to cat D, pay you a good amount of money and you buy it back for peanuts, you will have to then repair the car yourself though.
