Thriller - hotel room disappearance

Hello there. The opening of the plot is:

A gentleman walks into a hotel asking for a room. The receptionist says OK and gives him a key (say room 123). The man goes to room 123, opens the door, only to see it already occupied. A very very old lady in a wheelchair, leaning against a wooden stick, with ten thousand small items everywhere in the room (something you don't expect in a hotel room).
Upon going back to the reception he says the room was occupied. The receptionist insists it could not be the case. The two go together to room 123, open the door, and it is empty :)
The man says he's sorry and probably mixed up the doors, sends the receptionist back, closes the door, puts his luggage aside and sits on the bed. And then he notices the old lady's wooden stick leaning against the wall :)

Any help is greatly appreciated. Thanks a lot in advance.