What does the tracking show?
If it shows delivery to you, then you have 48 hours to refund the buyer. In my experience, Ebay don't chase you to refund until that 48 hour clock starts ticking.
You can get very good advice from the forum but adding more information will mean better advice.
If you really want to speak to Customer Services, use the link below. Currently there is a 19 minute wait time so you would probably find your answer faster by asking experienced members here.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)
