You have 30 days to return an item that's not as described via eBay, same for PayPal.
If you paid with a debit/credit card or ApplePay you have 120 days to issue a not as described chargeback.
Unfortunately, for items bought back in December, you're way out of time to pursue a refund.
If your seller is a UK registered business seller you may want to take some free advice from one of the online consumer groups or Citizens Advice regarding pursuing this via a legal claim.