The issue fits exactly with the terms of the Money Back Guarantee, you open a NOT AS DESCRIBED CASE with ebay and seller has to pay the return postage by supplying you with a label and on return refund.
The MBG is on every listing, you don't have to go through the seller, as you have found they can just ignore you but they cannot ignore an ebay case without risking penalties.
If it is dangerous then I suggest you have a ord with trading standards.
