Trex refuses to acknowledge that they have problems with mold and mildew. My deck is just over one year old and I have had it cleaned three times already with their recommended cleaner. Within 6 weeks the black spots come back and multiply. I had a pressure treated wood deck for 11 years and never had mold or mildew issues ... I just got tired of pressure washing and re-staining every few years. I should've stayed with the wood ... Trex is NOT worth the cost and is MORE maintenance than wood. After seeing several pictures like the one attached, Trex just sent me a copy of warranty explaining how mold and mildew are not covered ... and never offered to send out a representative, and I only live 20 miles from corporate office.
Don't feel like you're alone. I have exactly the same problem, it's probably worse, with my Fiber Composites deck. The response they gave me is the same they gave you. They refuse to acknowledge a problem and will not even give me the courtesy of sending a representative to inspect my deck. I live in NC close to their plant. They basically have ignored me. I just hired a lawyer and we'll see how long they will act like there's no problem.
Not to burst your bubble, they will most likely send you cleaning supplies, which you will have to do yourself. Spend your time and energy only to have the mold come back.
I've been able to find 2 current lawsuits, please join:
I also was duped by Trex's false advertising and failure to back up their product. I have black spots seeping out from the boards (installed summer 2010) even on dry areas of the deck with many hours of direct sunlight each day so this is clearly a product defect - not mold (mold likes damp, dark places - not direct sunlight). I'm filing a MA lawsuit for reimbursement so I can replace the decking with a different product - wish me luck. Notice in the attached photo that black spots are only on the Trex decking. None on the white Fiberone railing, or the house siding.