If you sent it through ebay, they’ll have to sort it. The buyer will have make the claim and chances are they’ll be refunded fairly quickly but royal mail will take about two weeks to cough up and for you to get reimbursed. That’s been my experience anyway...
Sold something and sent through eBays portal to send with Royal Mail. It hasn’t turned up. Is this a issue to bring up with eBay or with Royal Mail?