We booked a hotel through Trivago on Otel.com which should have been refundable and "pay at the hotel". Unfortunately, after booking we were charged for the hotel immediately and we couldn't cancel the booking as it turned out to be non-refundable. However, the worst was the communication with the customer line of Otel.com. They were not trying to help or even understand and at one point they stopped communicating with us. I tried to contact customer line trhough e-mail of Trivago as well but didn't get any reply for 2 weeks. Couldn't find a Czech phone number for the customer line.