[Bill Douglas]

A friend of mine was always too busy/too important to call me back. So when I phoned I said to his Personal Assistant "It's united video here, who you ask Mr. Patterson to return the videos Back Door Bride, Anal Frenzy, etc.. or he will be charged and extra day's rental." He called back reasonably promptly

I'm not really sure this would work in your instance. But it worked for me.