I don't know if you are able to get it where you are but in NZ we have a product called Brasso. Brasso is a metal polish and can be used on a variety of things, brass, silver stainless steel (great for exaust systems). The guys at the local boating club use it to clean and remove light scratches from the windscreens on thier very expensive boats. I have seen it used and the results. In my humble opinion it works very well.