Funds are held for all new and returning sellers as a security measure, eBay wish to see the item delivered.
If you cannot manually change the tracking where you marked the item as dispatched, you'll need to contact eBay Customer Services to change the tracking for you. Explain that tracking has shown delivery could they please release your money sooner.
To Contact Customer Services it's a Live Chat, or you can select to speak and request a Call Back. Click on this link:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
On the left sidebar you can see Have us Call you or Chat with Our Automated Assistant.
On weekdays lines open between 8 a.m. and 10 .m.
On weekends they open between 9 a.m. and 6 p.m.
@lbw*2010