Hi Anthony,
Have a similar problem with my R56 and also my wife's VW Golf 1K Having done a bit of research, it seems that after you polish the "fog" out of the lenses, you need to coat with some sort of UV protective coating. Some kits don't come with it.
You can also get a clear protective film to go over the lenses once they've been polished clear again, this may be another option.
If yours didnt, may be worth re-doing them and using that. I'm just about to order a kit to do mine.
Chrisfix on Youtube has a few good videos on how best to sort them, here's one: ChrisFix
Good luck
J