Pretty bizarre (Istanbul)

(Not a pretty bazaar :)

This is going to sound weird and I can guess the answer but there's no harm in asking as there may be some good advice out there.

I rent a room in Sisli with no contract i.e. there's nothing formal in place.

This morning I caught one of the landlord's Turkish assistants leaving our home with a girl and we discovered that he had spent the night here in one of the rooms! He must have arrived around 1am or later. We wouldn't have noticed except that I got up very early this morning.

Is there anything I can do about this?
Thx
Mark