A few years ago I fell of a porch roof while climbing onto my ladders, the ladders came down and left a really bad 8in metallic like scratch down the front window. After speaking to a fellow window cleaner friend he suggested using some jewellers rouge to remove said scratch, fortunately he had some because I wouldnt know where to get it. Anyway to cut a long story short I had to polish away at this scratch for an hour, at first you dont think anything is happeneng but slowly the scratch dissapears and it saves forking out for a new window.