Ebay gives the Buyer 4 days to pay.

If they don't pay - the Seller can then open an Unpaid Item Claim with ebay.

The Buyer then gets another 4 days to pay - if still no payment is made you can close the case (on the minute the 4 days is up ).

The Seller gets their fees refunded and the Buyer gets a strike for non payment.

Put them on your Blocked Bidder List so they can't bid again on your listings.