If your parcel shows as delivered on the Royal Mail website, you can contact Ebay and request that they release your payment.
Payment should be available 48 hours after tracking shows delivery.
What does the RM website show?
Use the link to get a callback:
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)