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.

You are too late to claim a refund from eBay,  but can try your payment provider,  most offer a 120 day buyer protection policy.

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.

@diolan13