Windex for the window and try to find fingernail polish of the correct shade for the scratches. Mix in a little white if you have to. Use the bottom of a paper cup or something small to make tiny batches until you get the mix you like (as plain black will likely be too dark compared to Gun Metal Black which is more gray.)
I used to work in a sign shop and you wouldnt believe the colours used to mix up to a certain colour., black, white, silver, yellow, red, blue, all used to make a slight off-black. Sorry thats the best i can suggest.
If all else fails take a side cover to a paint or sign shop and see if they can do a paint match, then mix a small batch for you..[/Q
Okay thanks, do you know any case painting services in the uk. to be honest i cba doing it myself