See if you can cancel the label. Find it on here:
https://www.ebay.co.uk/ship/lmng/labels-history/seller-hub
On the left of sales record there's a dropdown menu under "Actions". Click on that then click on "Void Label".
If you can't then you're using Simple Delivery and the only way to get rid of that is to cancel the transaction and relist while opting out of it during the relisting process.
Otherwise if you buy another label you will be paying for it yourself. You may be able to add the new tracking number via Order Details > Postage > dropdown menu (beside track package) > Add Tracking > + Additional Tracking Number. If not contact ebay and ask them to do it. You can use callback on here:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Simple Delivery will be compulsory from Monday see read up on it. You will have received an email about it from ebay.
