Input needed on a developing ebay buyer situation

[pokerplyr80]

I would contact Ebay and plead your case, let them know you are being scammed. I've never dealt with this situation personally on either end, but have a feeling they may side with the buyer. But presenting your side before he files a claim may help.

[tribefan]

What is the eBay id, and his name? He may be a known scammer. Is there anything in his feedback that appears to be a false positive?

[swarmee]

I'm trying to figure out how this makes sense from the buyer's perspective. It's not like a different PSA 7 could have been swapped out in the mail.
Option 1: If the buyer had Cert #144... beforehand and he wanted to "trade" it for your card, he'd be asking for a refund, not for you to send the card you actually were selling. Maybe this is a mid-game gambit that he'll negotiate back to you to return his #144 for a full refund.
Option 2: You made the mistake and accidentally sent him the wrong card. You have a collection of this specific card and you own multiples of them. Maybe you just forgot this one, and you mailed it accidentally. However, if this was the case, #179 is still in your possession somewhere.

Option 2 makes the most sense to me, just based on game theory and intuition.