I purchased some Singway 100w voltage converters back in October 2016.  They weren't used until Dec 2016 thru Feb 2016 then not used again until Dec 2017.  They have all failed by the time I used them again in Dec 2017.  Some even melted.  This is a highly dangerous product.  I went back through my purchase and contacted the seller to rquest a refund.  He emailed back and says he can't find my order which is clearly on my purchase history list.  I am unable to provide him my email address due to ebay rules which he has requested.  He still says after numerous emails that he cant find my order and I am unable to put in a returns request as it only gives me the option to contact seller, nothing else.  I tried to submit a return request for an item not received, but the item number doesn't come up on ebay so I am presuming it has been removed (not surprised as these things are **bleep**).  

How do I submit a request for a refund to ebay as clearly the seller isn't going to help me and there seems to be no way to do it on ebay either.  I am going around in circles here.  Surely there is still a warranty period and buyers are entitled to a refund outside of non-delivery and damaged items on arrival???