The seller lied, hoping you didn't understand eBay's 30 day MBG Money Back Guarantee policy, and they were proved right.
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. You're probably too late too, to claim from your payment provider, but could try there, now.
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.
Read eBay's 30 day MBG link below it could save you a lot of time and money in the future when buying on eBay.
https://pages.ebay.co.uk/ebay-money-back-guarantee/
@bikingsaxman41