If the label was purchased from eBay but not used because of the issue, you can receive a full refund, but may need to wait 24 hours for it to appear before cancelling.
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.
As you bought your own postage, you need to finalise the transaction now only on the Seller Hub here:
https://www.ebay.co.uk/sh/ovw
Go to Orders >> Awaiting Postage, click on the item then top left on View Order Details.
Far right from More Action drop down menu click on ' Mark as Dispatched' if you have it, add any tracking number there too.
@blueeuph