The hotel was overbooked, and could not honor my reservation.
I went to the reception at 13:00 the day of check-in, but was told that check-in did not start before 15:00. Came back to check-in at 15:15, but was told the hotel was overbooked, and that they hadn't received bookings from hotels.com for the last couple of weeks. They had rebooked me to a different hotel, further from the city and with a lower standard. The hotel was also half the price of my room at NH Hotels. NH Hotels still charged me for the full booking.
I understand that mishaps can happen, but in cases like this it can be handled way better. I do not understand why they did not proactively contact me earlier, or that they did not tell me about the situation the first time I came around to the reception. I will not book rooms at this hotel in the future, and will rather stay at Hotel Timisoara or Continental (which is also located closer to the city).