My flat smells!!!

[indauk]

I have just moved into a new flat, it smells. It's like a stale old cigarette, and windows never opened smell. I have tried everything- washed the walls, spray Oust all the time, cleaned behind the radiators (it was horrible- just big clumps of dust - I couldn't get it all out- anyone have a clue how to clean behind radiators?) Does anyone know how to get rid of these kind of smells? Thanks :)