Stains on Trex

Yes, the trees are not the problem, I bought trex to experiment with, built a nice 8 foot bench, I liked the material so months later re did my deck with trex, about $10,000 worth. Now the bench is FINE and the DECK looks awful. The bench sits on the deck and is un affected by mold..It has to be something in some of their production runs..Thinking about starting a boycott or picketing Lowe's where it was purchased...They have been no help..Spread the word and hurt their sales and maybe Trex will help us out..