ebay buyitnow help PLEASE

guys, i had an ad on ebay with buyitnow, the guy bought it and later called to check a few things, my fault i had the wrong spec of it so I issued him a refund but in my Ebay I see ebay have listed it as sold and have charged me the final fee so how do i go about cancelling this completed listing.

its completed/closed auction so i can't cancel bids and etc.

what shall i do? any help will be appreacited

PS: Merry Christmas to all......

Just send a email to the customer service explaining the prob and they should refund you,i had same probs in the past and the email done the trick...