They "forgot" to pay the damage deposit back - I asked and they said it was a mistake. Then I got 30 Euro back although I paid 80. There was definitely no reason for this but I never got a reply for asking for the 80 Euro.
For people who are interested in staying there anyway: My room way big enough to open the door and to have a bed inside. That's it. The bathroom was very dirty. I left the house after 3 days of 7 and moved to another place. To say something positive: The location is really good, a supermarket is close by and there is a very good public transport link to the city and the airport (bus 16). more