I and my friends booked single rooms several months in advance. I confirmed a week before. My friends called a couple of days before and were told that since they had not confirmed the hotel had sold their rooms. How difficult could it be to send an email and ask if you want confirmation?
When arriving there was no single room for me. Instead I was booked in a small apartment (one bathroom) with another person I did not know. Due the the AERO Messe all hotels were full so I either had to accept or sleep in a park. The apartment was in the old part next to an extremely noisy road crossing and a church ringing it's bells every quarter. They reduced the price from €83 to €56. With the noise and unknown person they should not have charged at all, since they were responsible for the mistake!!
No cold water in the morning and the first day Internet did not work. So if you book this hotel - book in the new building away from the street and confirm well in advance!