Absolutely nothing

We arrived at 9:30pm to loud music on the first floor shaking the building and the smell of smoke/weed. When we went up to the 2nd floor apartment we saw the bathroom was FILTHY! Body dirt, hair, and pubic hairs in tub with a used soap bar and pubic hair on it Toilet with urine and hair under seat. Sink with gobs of toothpaste on faucet and down the cupboard. I called the owner and told him we were leaving and I wanted a refund. At first he argued with me and said he inspected it. Then I sent him pics and he stated he’d refund my money. He agreed in a text it wasn’t cleaned. We had to find a hotel at 9:30pm on a busy weekend. I contacted Booking.com and they contacted him but he wouldn’t respond for several days. I contacted him and he lied and told me did approve my refund. He didn’t. Finally after several days and contacts to him and Booking he approved a 90% refund!!! Why should he keep 10% of my money?? No one would have wanted to stay there as dirty as it was! That wasn’t my fault and I don’t want to give him any of my money! He’s a dishonest businessman! Booking.com should not allow this kind of practice on their website. I will never rent a private property on there again. I’m still in the process of fighting for my additional 10% refund ! Unacceptable!!!