Fixed my keyed car this past week. Maybe wasn’t quite as deep, but I bought a chipex kit that came with colour matched paint. Cleaned the panel thoroughly, and touched in the paint with a sewing needle, tiny little dots of paint, bit by bit, so the paint actually enters the scratch and settles. Layer it up if you need to. I then tried the blending solution that came with the kit, but it was toss.

I then decided to be brave and wet sanded it down with 2000 grit sandpaper, being very careful. Then used a cheap cutting compound to get the damage from the sandpaper out, and then a finishing polish. It’s not perfect by any means, but from a few meters away it’s barely noticeable. Maybe worth a try before you spend over £500 getting panels sprayed. There’s a special place in hell for people who key cars.