Just trying to remove water from the C3 head light is hard enough so I would say. No cure just replace. After looking on ebay CLICK HERE it was just as cheap to buy new. Just remember to check you order the correct ones.
I used 1200 wet- dry to go over first followed by A Body Compound, as it was picked up by MOT tester last year. if it looks clear when wet the above may work its not going to make it any worse by doing the above. they are plastic not glass