We were supposed to pick up the keys at the parents shop, and then go to the flat in the same street. In the end, the father of our host came with his car and took us to another flat (not at all the neighborhood we wanted to stay in) saying that the flat we booked wasn't available and that we had no choice but stay here. I had to call the host to have real explanations and apologies but we had to stay in the flat that we didn't book in the first place.
The new flat was fine. but we didn't like that we had not been informed before, it took us some time to have real explanations about what happened.