You cannot report this to eBay as they do not offer warranties or guarantees on items, just that they are just as described on receipt. If they are not, a buyer has 30 days under eBay's 30 day MBG, Money Back Guarantee policy, to return the item for a full refund.
If you bought this from a Private seller you are too late to claim a refund. Too late to claim from your payment provider too.
I'm surprised when you reported this to Apple and they checked it, they didn't ask for any contact details of the person you bought the item from.
If purchased from a registered UK business, who offered a guarantee and is now not upholding this, then turn to Citizens Advice for your next steps, if you wish to take this further.
@reubz1