Assuming that you bought the adaptor over 30 days ago it will no longer be covered by eBay's money back guarantee. After this, eBay will not be involved, except pass on the recall notice for your information.
Any action required will be the responsibility of the seller. If you can't contact the seller or they're not helpful, you could check the manufacturer's web site for advice.
If it's just an ordinary 3-way plug adaptor it may not be worth the hassle. I'd probably just scrap it.
Remember that eBay warns buyers in the user agreement that "they do not guarantee the existence, quality, safety or legality of items advertised, or the truth or accuracy of descriptions". eBay can be a risky place to buy things.