I am sorry, but you have gone about this, totally the wrong way ,as you were entitled to a full refund, but only when following the rules for return of a faulty item, under eBay's 30 day MBG Money Back Guarantee policy.
You should not have binned the item.
When receiving an item not as described you have 30 days in which to open a case and the seller has 3 days to fully refund you or send a return label for the item's return. They are entitled to receive their item back.
On return they had 48 hours to refund or or eBay step in on escalation, and force the refund.
You did not follow the above, so eBay cannot help you here. Try your payment provider, see if they can help with your refund.
Read about eBay's 30 day MBG it can save you a lot of money and time when buying on eBay. It's written on every listing, and on the link below.
https://pages.ebay.co.uk/ebay-money-back-guarantee/
@5750hilary