As has been said, get onto the court ASAP and find out if a warrant has been served and which monkey did it!
Also contact the bailiff company and in no uncertain terms inform them that he does not, nor ever has to your knowledge lived there and that you will be persuing them for harrasment if they continue. Someone somewhere has dropped a huge clanger, a warrant is a very serious document and if its wrong then someone is in doo-doo!
Instruct all members of the household to only open the door to people they know, if they do not know the person at the door then do not open it... keep all windows closed.
Even though the law is on your side, if bailiffs do manage to gain entry then you will be fighting harder to get it sorted. If they appear and demand entry inform them of the situation and call the police if you feel threatened, if they have a warrant there should be police present in which case you inform them of the situation and go from there.
Best best is to get the magistrate/judge who signed the warrant to get their arse in gear and demand to see/speak to them to find out why they signed something thats wrong!
Good luck and let us know what happened.