Hi,
If all was resolved amicably with your buyers and it's within 45 days of listing end you can send them a 'mutual cancellation request' whereby you get the final value fee credit and the buyer doesn't get a strike on their account.
Let them know in advance why you are doing so, assure them there will be no detriment to their account and ask them to agree to it.
http://res.ebay.co.uk/ws/eBayISAPI.dll?CreateDispute&DisputeReason=2&guest=1
If they don't agree you won't receive the credit so will still have to pay the final value fee. If they don't respond, you can close manually after 7 days and will receive it.
If it's outside the 45 days, then I'm afraid nothing you can do except pay ebay.

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