Hahaha!!! I'm falling out of my chair here, bro!!!
Maybe it's that simple??? I tend to think not, but it's certainly playing out that way!!!
One thing's for sure, if that guy runs his business this way, either everything he has in inventory is stolen or he's just running it in the red.
Personally, I think he was trying out something illegal and that's why you got a call from the third party guy claiming he was from a credit card company. Something went wrong with their little plan and the only way to make things look "legit" is to back-track quickly and completely. The e-mail you just received, along with the expedited mail sending you back your payment, along with not asking for the product back, gives their "story" certain credibility. That credibility is what they need when the "caca hits the ventilator".
Either way...
Merry Christmas!!! LOL!!!