Never Ever use a plastic scourer on glass

OK I know, it's April, but I finally decided to get around to removing the "Santa Snow" sprayed onto the lounge room window. I tried windex and a soft sponge - no effect. I tried spray and wipe with the same sponge - still no effect. So I tried the back of the sponge-scourer - scrubbing in circles trying to get the darned sticky stuff off. It had some effect, but I thought it was just smudging it into an opaque smear. It was only then that I realised to my horror that I was actually scratching big marks into the glass :(:( Needless to say I am not happy jan! So now I have this Christmas Tree-shaped patch of scratched glass right at eye level. :( Does anyone know how to polish glass?