Fake shoes. What to do? Seller exposed themselves on Twitter.

[Saeedawawd]

Hello Paypal people,

I recently bought shoes from a shoe site, and I paid $180 USD while the retail was $170 as the shoes are limited. For those wondering, it is the NMD PK White gum pack. I get the package today, and I open it, and instantly notice the word "Boost" is on the insole of one shoes, and not on the other, while it is supposed to be on both. I legit check the pair I suspect is fake, and I found it to be fake. I watched multiple unboxings and looked at multiple listings of the shoes, and they all had "Boost" written inside both pairs. I twitter message the seller and told him to refund me, and he tells me that they are real, and that I switched one pair with a fake one to get my money back and get the shoes, and he inisted that they are real, and that he knows everything about the shoe. He did send me a confirmation email from Urban Outfitters, so I google his name, and I found his Twitter, and a tweet that he sent out right after our conversation, proving that he was not even sure that the pair he sent is real. How do I go about getting the refund, as I have this very legitimate and effective proof in my case?