It's poor sportsmanship, but unfortunately all you can do is wait it out. Be comforted that eventually you will have the win. In the meantime just keep playing other people and enjoying the game.
Deliberately extending game

Hello all,
My oponent was already on vacation before and just now have changed her status to vacation again. The game is lost, but she takes long to move and now apparently there will be no moves at all for some time.
Is there any rule to prevent this behavior?
It sounds like 'Vacation Abuse' and can be reported, see this link...
http://support.chess.com/Knowledgebase/Article/View/104/0/what-is-vacation-abuse
Hello all,
My oponent was already on vacation before and just now have changed her status to vacation again. The game is lost, but she takes long to move and now apparently there will be no moves at all for some time.
Is there any rule to prevent this behavior?