Ok everyone, let's all step back and take things down a notch.
Litz,
Perhaps there's a problem with your Landmark that the rest of us haven't experienced. It seems to me that there are two approaches you can take. One is to go to a dealer or independent servicer, as some have suggested, and see if they can resolve the problem for you at a reasonable price. Perhaps your selling dealer will help. The other approach would be to address the problem the same way people do when sealing drafts in a sticks and bricks home. There are all kinds of draft stoppers available at hardware stores and many other places.
These approaches may fall short of your expectations in buying a one year old luxury RV. But speaking frankly (and not intending to be in any way mean or snarky), you do have to accept some risk along with the good deal that comes when buying used. I suspect at the end of the day you'll still have a great deal and will enjoy your Landmark.
Whatever you end up doing, if you could circle back around and let us know how you resolved the problem, who knows, it might benefit someone else down the road.