The most likely reason is that someone used your computer to log into their Ebay account, and they either didn't log out or they saved their Ebay login details... Or someone has hacked into your Ebay account (easy to do if your password is guessable or weak) and possibly the other member's account too which is how they've been linked if you don't know the owner of that account... Or you've inadvertently given away your password/s, possibly by clicking on a link or links in a phishing email... Or someone you know has used and made changes to your account......
Who knows for sure. But whatever has caused this, it won't be Ebay. It is up to you to keep you and your accounts safe and secure online.
If necessary, check your computer and other devices for possible malware, and change all your passwords immediately. Make them strong and totally unguessable, and don't share them with anyone at all, not even trusted members of your household. And don't let anyone else use your computer or other devices.
You should also consider doing a web search for 'staying safe online' so that this or similar can't happen to you again.
@blackwoodgov
