Nobody seems to read the user agreement!
Section 2 makes it clear that sellers are entirely responsible for their listings. eBay even warns buyers that they don't guarantee that items sold here will be safe, or even legal.
Atter eBay's own 30 day money back guarantee has expired they have no further responsibility or interest. They will pass on recall notices to buyers, but responsibility for any action required rests with the seller.
Many eBay sellers don't want to know, in which case you can only try the manufacturer, to see whether they can halp, or consult itizens Advice or Trading standards, if the seller is in the UK. You might even end up having to bin the item.
These are just some of the risks of buying from unknown sellers here. Buying on eBay isn't like the shops.