There was a tv drama a few years ago (over 3 years at least) about a couple that returned home to find a stranger in their home. They mistakenly took him for a friend of a friend that was due to come to stay and he then slowly made their lives hell.
I cant remember the actors or who wrote it. I think it must have been on either ITV or channel 4.
I know its a long shot but any ideas? Sorry I havent been more help!