I do agree with Linus that the official cost to repair is excessive. If I were to submit that claim to my own insurer, they would surely write the car off (and in my verbal report to them, they already hinted as much). And this is one reason I drive in a minimum-risk fashion these days (also because, as a bike-rider, keen attention to risk is a survival habit).
All I want is the car put back the way it was, and if that can be achieved at half the Lexus dealer's estimate, I'm happy with that. My understanding is that a primary principle of insurance is maximum good faith; it is easy to lose sight of this. But it is beyond annoying to be asked to do the legwork to mitigate the final cost when one is the injured party. And I don't have any experience of, or appetite for haggling with the motor trade.