Then you can claim back your FVF and leave feedback (if you wish) to which they cannot respond as they relinquish their rights to feedback by not replying to an unpaid dispute.
I would then add them to my blocked bidders list to prevent subsequent acts of lets say vandalism to your auctions.
Do not get involved at a personal level by making verbal contact, it is unproductive and unverifiable if it gets ugly. Any communication should be by contact buyer/seller.
What ever is said by eBay, a winner cannot be forced to pay except by suing them for breach of contract at your expense !
eBay will step back and say we are only a venue, tough
Please see my and biscuit's earlier posts on this thread, then sit back and do something more useful like preparing more listings for the worthwhile buyers.
P.S. sending an item to defaulter who has been coerced into paying up, may leave red feedback saying you were an impatient bully. Worse falsely claim for non delivery, worse still start a charge back fraud. Beware
