If it's still within 120 days of payment contact your payment provider and ask about a refund or chargeback.   

What sort of case did you open as a Not as described case cannot be ignored, or a Business Seller has to accept any return case.

Sounds like you did not open a proper claim or you were outside the 30 days. As said if within 120 days contact payment provider.

To save you time and money on future eBay purchases,  read how their 30 day MBG,  Money Back Guarantee works,  from the link below.  

As advised by others,  outside this period you have 120 days to claim with your payment provider.

Turn to Citizens Advice, if this was a UK registered business,  not upholding any given warranty, and you wish to pursue this further.

https://pages.ebay.co.uk/ebay-money-back-guarantee/

@8sally63