Check you have correctly added your bank account details here:
https://ppcapp.ebay.co.uk/myppc/wallet/list
You may need a PC / laptop and not the app or mobile browser to do this. Use Chrome or Firefox they work best with eBay.
If there is still an an issue, access to your account is needed, and for this you need to contact eBay Customer Services.
To Contact Customer Services, I find the quickest way to contact them, either for a Live Chat, or you can select to speak and request a Call Back, to click on this link:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
@beck.hump
On weekdays lines open between 8 a.m. and 10 p.m.
On weekends they open between 9 a.m. and 6 p.m.