Ebay sometimes takes a while to catch up with carriers' websites.
48 hours after the tracking shows delivered on the Parcelforce website, if the tracking has not updated on Ebay, you can contact Customer Services and ask them to manually update the tracking and release your funds.
"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)