Only the seller can refund, because only they received your money. We make it automatic from your side:

• Overpaid: you get the piece; the difference is refunded.
• Paid twice: the second payment is refunded.
• Underpaid: send the rest within 2 hours, or what you paid is refunded.
• Paid after the 30-minute reservation: the order re-opens if the piece is still available (within 2 hours); otherwise you're refunded.
• In review: if a payment can't be confirmed within 12 hours, it's refunded.
• Paid the wrong seller: that seller is asked to refund you.

Sellers have 72 hours to send a refund. If they don't, you're paid from their refund bond in USDC to the wallet on your order, and their checkout pauses until the bond is topped up.