Have you the correct payment details here for paying fees?
https://ppcapp.ebay.co.uk/myppc/wallet/list
Use a laptop / PC not the app if you need to change anything.
If your details there are correct and there's still an issue paying those fees, contact eBay Customer Services for them to help you.
This is the easiest and quickest way to contact eBay Customer Services, for a Call Back option.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Lines open 8 a.m. - 10 p.m. on weekdays
9 a.m. - 6 p.m. on weekends.
Automated agents will be available on chat outside of the above hours.
I recommend contacting CS first thing in the morning as there's more chance of Dublin answering.
@sa-857232