Need a good Porsche Appraiser for diminished value claim

[Crachian]

I'm pursuing a diminished value claim stemming from this damage to my car.

I'm getting it straightened out and painted now, but because I am having the entire car painted and the insurer only agreed to paint part of the car, my worry is that it will be difficult if not impossible to determine the diminished value following repair.

Has anyone any experience with a pro-owner Porsche Appraiser including any of those advertising in Panorama?

Thanks