From the first day that I purchased and took delivery of this new 2015 C300 MB car, whenever I turn on the HVAC system I have had this bad, moldy, musty and obnoxious smell/odor inside the cabin. This smell is sickening and unhealthy. Since I first purchased this car I have continuously informed my MB Dealer about this bad unhealthy smell. I called the Dealer's service person several times and left him many messages describing the bad awful smell. The service/maintenance person never returned any of my voice messages. Then I drove to the Dealership and waited to see this service person. Finally, a few days ago after I continued to insist, the Dealer agreed to replace the cabin air filter and perform a "Biopledge Treatment" at no charge. Even after the cabin air filter was changed and the Bio treatment performed, NOW, I continue to have this unhealthy, musty, moldy and obnoxious smell. Again, I reached out to the Dealership to find out if they have any other solution to this continuing bad unbearable unhealthy odor problem.