Are you sure its faded? I would be surprised to find a Leon that has faded yet.
If you are sure it has, try the Klasse twins - two products, one is a all-in-one chemical cleaner/polish that will
help remove some of the oxidised paint, the other product is a sealant to be used afterwards that will
help protect the paint against further UV damage amongst other things.
Best solution of all is to have the car machine polished properly (i.e. detailed) by someone local who knows what they are doing.