Charming Stay in Marvelous Seattle

We're disputing the charge with Airbnb and the host. I feel like we were robbed of $3,500 for my daughter's University of Washington graduation weekend. We booked what was presented as a single-family home, but no one told us people lived in the basement. It's connected to the part we rented by a stairway and door inside the house. Four men got out of cars and hung out under the deck behind the home. We could hear them talking, and the place smelled strongly of cigarettes. I went downstairs and asked one of them if he lived there. He said yes. I've documented that conversation and the host's continued twisting of the truth. The booking was made ten months ago, and I'm still trying to get the charge reversed. I bought the insurance, but it has been useless. Airbnb is backing this slumlord, and they won't get my business again.