DON'T use scourers, green or metal. They scratch!
I'm a window cleaner, I use DoKtor power (JML product) for upvc.
I've used various upvc cleaners and found this the best one to use. You use the sponge that it comes. First you wet the sponge, rub it into the product so it foams, then rub it onto the upvc. Then you wipe it off with a dry cloth.
Hey presto... Its clean and looks great.
I mainly use it on the inside of conservatorys and my customers are extremely happy with the results.