Personally, I think it's probably best to cancel that label receive a refund, link below will explain. Then, take the item to a Post Office let them weigh the item, and they will correctly charge the right price.
You may then need to contact eBay Customer Services if you cannot later manually change the tracking number. You will also have to manually mark the item as dispatched too.
For a refund on the unused label, it may take 24 hours to appear, 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.
If you need to, 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 between 8 a.m. to 10 p.m. on weekdays.
9 a.m. to 6 p.m. on weekends.
I recommend contacting CS very first thing in the morning, when the lines first open, as there's more chance of Dublin answering.
@iavt9249
