A friend of mine's son was playing his toon on his account. He had not blocked the chat channel invites on his sons's computer and his son clicked on the chat invite thinking it was a group invite. When he logged off they stripped all his toons and banks and deleted all his toons, but one they left naked. He talked to blizzard and all they kept saying was you should have known better and your son should have known better, But they will investigate and get back to him in 5 days!!!!!!!!!!!! They did say they have been getting calls for this repeatedly.
So, be sure to block chat channel invites ! Main Menu - Interface Options - Social - Check mark Block Chat Channel Invites
Blizzard said to report each one that shows up in your chat channel so they can get a handle on this problem.