Terrible airbnb experience, and a $12 refund

I had a 2 night stay at a home in Marin county this past weekend. The host said she’d be out of town and my mom and I would have the home to ourselves. We arrived to find the key sitting in a basket clear as day at the foot of the door and was told to leave it there when leaving. The risk of this to my property is quite obvious. The house was not very clean at all, but at that point I wasn’t ready to quibble. The first morning we leave to have breakfast and come back to find 2 keys in the basket, go inside and find lots of new items in the one bathroom. I peek in the spare bedroom to find loads of unpacked luggage. I had slept on the sofa since I had asked the host if there was a sofa or something I could put on the floor to sleep since I don’t sleep with my mom. The response was ‘people make it work’. Ok. So I collect my belongings by the sofa and put the sofa back together, since I assumed maybe the host had another airbnb guest, but I was angry about no advance notice of this since we were told, ‘you’ll have the house to yourself’. I tried to reach the host to ask what was happening to no avail. Finally I get a reply that says only, ‘that is Stacy, she texted me this morning, and I don’t like for people to sleep on the sofa’ Ok, that isn’t going to cut it. Is my stuff safe? Are we safe? I slept on the sofa because no one was home and I was ‘making it work’. It was too late to leave and get a hotel room, because we had to drive far to a wedding. We arrive back at 10pm and it seems ‘Stacy’ is still out. At 1am they (2 people) arrive and noisily use the bathroom, which of course is directly across from our room. At 1:30am begins a 15 min vomiting session in the bathroom. I get up around 4am to use the bathroom and the genius had used the SINK to throw up in and there is vomit everywhere. At 6:30am we leave, brushing our teeth in the kitchen sink. I contact the host and tell her that it was not appropriate not to tell us she was allowing her friend and boyfriend to stay without notifying us. How is that not self evident? I also spoke of the vomiting to be assured it wouldn’t be blamed on us. What kind of person doesn’t clean up their vomit when 4 adults are sharing a bathroom? As compensation maybe in her tiny mind to prevent a bad review, she offers to refund $12 of a $225 rental or offer 50% off the next stay. Right. I assume that I have no recourse since this type of situation is not addressed in the refund policy, but this was the second time using airbnb with my mom, the first featuring a 4 year old running around touching everything and hours later being told he was diagnosed with pneumonia the day before. My mom is 76. I guess the lesson here is that many hosts don’t give a sh*t.