Not sure how big or bad the scratch is but I've used the Dr Colorchip (check it on Google) stuff on a couple of scratches and chips. It's maybe more for stone chips than scratches but I found it worked great. This is from the website
•Deep Scratches - Deep, narrow scratches (1/16" or less) down to the metal will usually hold paint. As our paint is instantly malleable (in this case, tacky, yet removable), there is some flexibilty in finessing the paint into place. The various brushes in the kit also allow for more precise painting of scratches that can't effectively be repaired by our standard process.
•Wide Scratches - Wide scratches (1/16" or greater), gashes or other large defects will likely need to have the paint applied and left as is. Filling and spraying these types of damage is the only way to get a 'like new' repair.
•Light Surface Scratches - Generally these can be buffed out. If you can feel them with your fingernail, they might come out completely with some wet-sanding and buffing. Otherwise, our precision brush can be used to lightly apply the paint over the scratch and left as is.
•Key Scratches - We dont recommend buying our kit soley for fixing key scratches unless the vehicle color is dark, and the scratch is short and deep. A long key scratch on a light silver or gold car will show almost no difference, even if the paint completely fills the scratch. However, if you are not inclined to pay for a body shop repair, the special brushes in the kit will help you make the best repair possible.
•Vehicle Color - The color of the vehicle also determines the quality of the scratch repair. Darker colors always look better than light ones. A scratch on a black or dark red metallic vehicle will always look better afterward than on a light silver or gold one.
The stuff ain't cheap as it is in the States and has to be shipped but it arrived in a couple of days for me.
Not sure why it isn't sold here as somebody could make a fortune with it. It does actually do what the ads say on the website. They do mention it works best on dark coloured cars and I have a cadoxton grey and it worked a treat on the stone chips on the bonnet.
Hope you work something out anyway and it doesn't cost too much.