I had booked a room for one night. I was coming with the ferry from the islans and would arrive in Athens very late at night (midnight) so I immediately informed the person, both via mail and via phone that I would be arriving that late. The same morning I called again, just to make sure that they would know and that they wouldn't think I wasn't showing up. They literally said "no problem, we know you're arriving very late!" Well, of course I arrive around 1 in the night and THERE IS NO ROOM.
I we want, they can put us in a sort of STORAGE ROOM for a cheaper price. It was night, I had no idea where to go, all the other hostels around were full booked and we had big luggage so we had to accept. The room was about 1,5 meter x 2 with a small bed, filled with old objects, dirty, disgusting bed linens, NO AIR, just a small window that you couldn't open, no toilet of course. We had to use a disgusting, dirty common toilet.
Don't go there, it's a total total rip off.