just send a good complaint explaining exactly what this user has done and everything u know about what happened.. don't be too clever though sound like u really need help and that u'r just a "poor little Internet user". If the mail doesn't help and it happens again then send another. If it happens a third time... hmm... CALL 'EM AND SCRIEM THEM HALF DEAF!
that's what I always do... now remember it's good to sound a bit dumb if u call them but if u feel u'r talking to the typical "computer illiterate support-line wannabe" just sound like some1 very clever and important... now this as u probably know is called social engineering hehe. it works wonders if used correctly