nothig you can do except an unpaid item dispute
its classed similar to unsolicited goods The unsolicited goods and services act used to give the seller 6 months to arrange collection of the item but law was amended about 3 years back and now the buyer has the right to keep genuine unsolited items as a gift as soon as they arrive
The theft act says it is an offence to seek to benefit from the errors of others.
End of the day you most likely have to write the item off especially if you are a private seller
You could tell the buyer within say 30 days of delivery that you are arranging collection of the item
But end of the day if they won't return it you would have a costly legal problem getting the item back
create a dispute after 4 days minimum time complete after another 4 days you get your final value fees he gets a strike
http://rebulk.ebay.co.uk/ws/eBayISAPI.dll?CreateDispute
do not choose mutual as if they don’t agree you lose your fees and they get off the hook
add to your blocked bidder list
http://pages.ebay.co.uk/help/sell/block_bidders.html
and block bidders with 2 disputes against them 12 months from your prefs
http://offer.ebay.co.uk/ws/eBayISAPI.dll?BuyerBlockPreferences
buyers cannot be left negative feedback or negative comments on positive so leave no feedback or buyer can get it removed and you would be penalised on your seller dashboard

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