Do you have tracking? What does it say? eBay's tracking is sometimes slow to update so try Royal Mail's Track & Trace online or the courier's website, what does tracking for the item say there.
Bottom line is if the buyer opens a case for item not received, entering a tracking number showing delivery will close the case in your favour. If tracking is not showing delivery, and you have used Simple Delivery eBay pay for that refund, and you get to keep the payout for the item.
If you used your own postage not SD, with not tracking showing that delivery, you need to refund through those case details and do so within 3 days so your seller performance is not affected.
@lucky7_red
