First of all, the hostel is amazingly located and rooms and facilites are in good condition, no reason to complain. Top money for value!
However there were a few problems with the booking process. When I requested a 10 people dorm, they responded and told me they only had a bed in an 8 people dorm and that I should request a stay in this room and accept the alteration. However I didn't respond within the 24 hours of my initial request (some people are actually working) so, instead of waiting for my response, they just confirmed my inital request saying that I had to pay the difference for the upgraded room. I then told them that I am not okay with this, paying more without ever agreeing to it. After a long discussion they renounced the extra charge as "not to upset me".
This is not about the amount of the extra charge (which was at 1€ ridiculously low) but about charging extra in general without consent when the client has no option to resign from the agreement due to cancellation policies.
However after it was figuered out, I had a pleasent stay.