Scratch on paintwork

There must have been a bit of grit on the inside of my car cover last time I put it on - when I removed it this morning, there is a 6 inch vertical scratch (down to the white) on the rear 1/4 panel. Most annoying.

Has anyone had any experience with Chips Away, as from their website it appears they may be able to do something without resorting to repainting the whole panel - they list vandal damage as the type of thing they do (Ok so it wasn't a vandal - I'm guilty of scratching my own car).

Cheers
Eric