Like Miss Whiskey said, there is not one damn thing the Admins and Mods can do about this stuff.
Which is why it is part of the rules of the Trading Post section.
Speaking as a private member of the forum and not a moderator, I would love to be able to think that every member of the forum is a class act and will honor their personal commitments.
Sadly, this is not always the case.
We seem to have new members showing up out of nowhere and their first post is wanting to sell stuff. Or trade stuff, or buy stuff.
I would suggest that before you decide to sell or buy or trade, take a look at their profile and then make the hard desision. Can they be trusted?
If they screw you over, and you have contacted them via PM or any other method at your disposal and they refuse to reply or make it right by you, then the last option that is open to you is to publicly post all of the gory details in the Hall of Shame and ding their trading score.
Which at least keep you fellow VU members from being taken as you were.
Wish I could do more but sad to say, you are on your own.