I’m so sorry you’re dealing with all this. Unfortunately some of those life lessons we learn come about this way. Once we had a dude take down a couple trees from the yard, and he needed to come back the next day to finish raising the tree line and repairing my favorite tree he destroyed in the process. My husband went ahead and paid him with the promise of returning the next day(not my style of business personally)…I imagine you can see where this is going.
We never saw the dude again. I thought the best of him for a couple days, and finally admitted to myself that we got the shaft. In our case we mostly got our moneys worth, so I let it go because I got strong vibes the dude was dangerous. The whole thing was a big pain, and I’m sorry this situation is occupying your mental load. Have you heard from the seller any more?