No need to contact eBay.
If there are funds in the Available section of your Payment Summary, this is taken first and not from pending funds.
If there is no money in the Available section, then payment for refunds or postage labels is taken from any pending funds.
To receive a refund for the unused label bought from eBay, l see below, you may need to wait 24 hours for the label to appear before you cancel it for a refund.
Find your label with this link .
https://www.ebay.co.uk/ship/lmng/labels-history/seller-hub and to the left of the sales record there is a drop down menu under 'Actions' click on that , then click on 'Void Label'. The refund will take between 5 - 21 days to process.
@tange-jap