Sorry to sound like an old fart, but this is one of the reasons that National Service should be brought back. In the services, when you get somebody like Jane who doesn't know right from wrong and think they can do as they like regardless, the best way of punishing them is to punish EVERYBODY ELSE in their 'company'/squad or whatever you want to call it - in this case, "the house". That way, the rest of them soon deal with the culprit in their own sweet ways, usually by doing something quite nasty (understatement of the year!) to them, and the message that their silly behaviour will not be tolerated by the majority soon gets through.
Unfortunately, the rest of them in the house are such super-wimps that it hasn't dawned on them to"get her seen-to". In the old days it would have been a "tar and feather"/boot polish treatment in the genital area, but even as a simple little thing for the housemates to do to the fat one, they could have "sent her to Coventry" (no speaking to her), made her sleep out in the garden with no bedding, destroy some of her make-up, and it could go on and on, getting progressively nastier until she learnt the lesson that in this life one has to live by certain rules to avoid anarchy.. Even for a simple starter they could have taped her gob shut - that would have given us all a treat!
So you see, it's not BB who's letting us down, it's the residents.