Hi Antonia, pretty scary hacker story,
I had my old eBay account hacked, but not taken over completely like yours. I was only made aware of the issue when I stated receiving emails about World Cup football tickets I had up for auction, which was news for me as I never had such a thing.
First email I dismissed as a joke, then when I checked my inbox next I had about 10 emails regarding the same. So I logged into eBay and sure enough, found the listing for World Cup tickets on my account. Of course the hacker had asked people in the listing to email them direct, not through eBay, but thankfully many were ignoring that request and using eBay which in turn then alerted me.
So thankfully we could rectify that hack quickly and effectively, but it does highlight the issues that are around and as per both our experience, need to have a careful eye kept on them.