Using a laptop / PC and Chrome if you cannot manually edit that tracking number you'll need to contact eBay Customer Services and they will change those numbers for 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
I recommend contacting CS early in the morning as there's more chance of Dublin answering.
@hep6210