Sold a duped Genuine Robo-Sandvich at TF2WH at full price

Hi,
I was sold a duped genuine Robo-Sandvich at full price on TF2WH.com and they refuse to facilitate an exchange. They stated that they do not discern between duped and non-duped items. As such they willingly sell duped items at full price with no forewarning of this policy nor of the item's status. In response to SIVARTZ |RAWR[A] 's appraisal of 1/2 price of a non-duped version, they stated that he is trying to play me for a cheap deal and will quickly resell it at full price.
Unfortunately, the item history didn't update for an extended period of time for me to see it's status until it was too late. It looked clean at first.
Despite not advertising their policy of selling duped items without disclosure or price adjustments, they refuse to help me, stating that if they helped me, they would have to help everyone that unwittingly bought a regularly priced duplicate.
They also lowered the stock limit after I asked for assistance on their forum. They are overstock with no way to trade the duped item back at a loss.
Item History:
http://backpack.tf/item/1123702138
The item is in my backpack AND the previous listed owner's backpack

TF2WH Thread:
http://forum.tf2wh.com/threads/sold-a-duped-genuine-robo-sandvich-at-full-price.4674/#post-35038

This is something you'll have to work out with WH directly, which you already are, making this even more of a false effort. We can't help you.

There is nothing shady about that, hardly anyone ever lists their items as dupes.