Did you perhaps buy the item as a Guest Purchase?
The best option is to get a new confirmation email using this link - https://www.ebay.co.uk/help/guest-order?topicId=4065&af=2.
From there you will be able to select the view order details to open a case .
If you are unable to do so from that point on you will need to speak to Customer Services, they can verify that you are the person who made the purchase and assist you with opening a claim.
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