Fix for Elantra problems?

I bought a top-of-the-range Hyundai Elantra last Christmas and the car was fine until the weather became colder. It wouldn’t start properly and fumes were coming into the interior. I contacted my dealer and was told Hyundai was aware of the problem but it still has not been rectified. I believe this is a health issue as the fumes are excessive. I am not prone to exaggeration. I love the car and I’m just wanting the problem to be rectified.