I would send photos of the letter to Airbnb and let them know what happened. I do not know where you live, but unless they took photos of the hair in the bathroom, and your cleaners don’t have black hair, than I wouldn’t worry about. You need to post a honest but diplomatic review of the guests. If you aren’t sure how to do that, talk to most calm and yet most well mannered friend. Because when they review you, you get to respond. We had a guest leave us the most insane review, the guests that came right after were so lovely, they left use the longest review and counter said everything the bad review said. I am am very southern though and people tend to believe me when I say I care. I have washing machines break, plumbing issue, refrigerators go out, even the AC in July, and still got 5 stars. It is all about how you handle it.
However, some people just complain, because they want a refund. I had one guy say internet wasn’t working. Wanted a refund. Called Airbnb and demanded it. I thankfully had another guest in my house and showed the text where guest told me he reset the router many times and it didn’t work. I asked him which one, the white or black? He said the only one in my room. I responded with that is a TV box. The routers are in living room, on the desk, one is white and on is black. He called me a liar so I send photos, texts, and phone call times to Airbnb. When he tried to leave me a bad review because I refused him his money back, Airbnb didn’t post it.
Being honest but polite is the only way to handle these things. If a guest has complaints but doesn’t have the balls to say it to your face, then they lack communication skills and get no stars or 1 on communication. I am honest. If they didn’t want to wash their dishes, there went cleaning stars. However, I do not know the true whole story. But anytime there is a damanding guests, I let Airbnb know. Also I didnt see your listing link, making sure to take the time to fill out everything in a very detailed way is important. Use your computer, and fill everything out all the way. House rules and such, every description and make sure your bio also explains not only you, but how you plan to host. Your style of hosting if you will.
Not ever guest is crazy, But around 20% are. Being prepapred to handle them is important and will say alot about you as a host!
I hope things change in the future. Take everything with a grain a salt, and as my momma says “treat everyone as an elder, regardless of how crazy they are, we do not know the miles they walk in their shoes.” Meaning we never know what their side is, ever. But we can always be the best version of ourselves.