Unpleasant Stay at Hostel Center Luxury in Sarajevo via Booking.com

I booked a stay at Hostel Center Luxury in Sarajevo through Booking.com and paid online. My confirmation number is 4305340***. On July 11, I arrived around 5:30 PM for check-in. I waited for about half an hour for someone to arrive. During this time, I had a chance to look into a room and use the restroom. I noticed that people had been smoking in the room, using empty water bottles as ashtrays, and I took a photo of it. After reaching the hostel manager by phone, someone finally arrived and showed me to my room. One of the guests in that room was smoking, and when I asked him to stop, he said he always smokes there. The room reeked of cigarette smoke. When I mentioned that smoking was happening in both rooms and that I wouldn't stay there, the employee who showed me the room became very aggressive, started yelling, and then made threatening remarks. I reported this to Booking.com the next day, but it has been over a week, and I still haven't received a response.