Cancelling a Sale in eBay which is already refunded via PayPal

[divingcraig]

I recently listed an item which was purchased as Buy It Now and the buyer asked me to send it urgently.

I purchased the postage with the intention of posting the next day but the buyer subsequently asked to cancel the order as they had bought the wrong item and requested a refund.

I advised that I had paid the postage already as they had asked for it urgently so they agreed so a refund less the postage cost.

I processed this via Paypal as it was not for the full amount.

Now I can't cancel the order via eBay as it says it will credit the buyer automaticvally which has already been done and it would be for the wrong value anyway.

How can I now cancel the item sale and therefore not incur any eBay fees?

Help much appreciated.