Just had a client who id previously seen a few times turn up unannounced out of the blue.
Fortunately I'm in a block, but he used my working name over the intercom, which can be heard in the stairway. Told him he had the wrong place.
I've just text him to basically tell him off and his excuse was that he had a new phone, had lost all his numbers, couldnt find me online so thought he'd drop by to get it. 
Middle aged short asian guy, Ravi 075978226**