A Guest purchase perhaps ? which will not appear on your eBay account summary --- can be found here >
Using a PC/Laptop, --- see if you can find the email Guest order Transaction number details using the Blue button in the link below --- Case options within 30 days from sale are there if needed >
https://www.ebay.co.uk/help/buying/returns-items-not-received-refunds-buyers/returning-item/returnin...
https://pages.ebay.co.uk/ebay-money-back-guarantee/