I am beyond fed up with this sh*t
I am so sorry that this has happened to you.
I know that whenever this has happened to me I have called them out in the thread in hopes that other artists won't go through what I have, and to hopefully ensure that that person never gets any more requests filled!
I was contemplating opening back up my queue but I think I'll leave it closed for a while now.
PS. THIS is why I won't do anything larger than a sig (unless I trust the requester)
I am not going to waste 5-7 hours making someone a wallpaper/twitch/etc only to find out they have PM'd multiple people.