The foggyness is caused by the Uv rays of the sun, mine were like that so i did some research on google and I found a cheap solution and that's baking soda, get a brush, a tooth brush for instance and put some on the headlights and brush it off and then rinse it off and dry it. Once you dry it, you should see a significant difference and you can see if there are any more foggy parts, in which you can just repeat the process.

 

brasso works alright too