We were overbooked. Nobody answered to the phone number provided by the booking confirmation. We have learned about the overbooking by the manager of a guesthouse next door, who was all the time our only contact to the owner/manager of the property.
We were promised to get to the (already fully payed) apartment next morning.
Indeed, we have received the keys from the above mentioned manager next door but the cleaning service did not arrive before 2 pm. And they have really only changed the bedlinen and towels. The bathroom and kitchen (even cookware) have not been cleaned at all.
The apartment needs a thorough cleaning of kitchen cabinets, wardrobes, floors, windows, shelves, tubs and sinks, and also a repaint.