Ebay should have never allowed or started to let people sell miles and/or vouchers on-line. Legal or not airlines never did like it.
http://news.com.com/2100-1017-866398.html?legacy=cnet
Ebay took its sweet time adjusting and even now allows it to be done under certain conditions.
Original OP did the wrong thing...but so did Ebay in misleading folks to think it was okay to do it.