If this seller was selling fake items buyers must have opened enough cases to bring this seller to eBay's attention and if you cannot see the selleron eBay, it's because they've been removed and banned from selling on eBay's site.
If you wish to return an item for a full refund contact eBay Customer Services now they will help open that case for you.
To Contact Customer Services it's a Live Chat, or you can select to speak and request a Call Back. Click on this link:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
On weekdays lines open between 8 a.m. and 10 p.m.
On weekends they open between 9 a.m. aand 6 p.m.