Those are gil sellers for sure ... thats the kind of name they actually use.

I know this isnt the appropriate time for it ( since everyone is complaining about servers and making a shit load of useless ticket on S-E support site about it , just like they think S-E never noticed .. ) but you should seriously contact them so they kick out the actual user, change your password as soon as possible, meanwhile do a scan on your computer with softwares like Malwarebytes Anti-Malware, Combofix ( by sUbs, find it on bleepingcomputer.com) and using Ccleaner to clear all your Temp files by the same time.

Also, if you have a cell phone, I would concider using the S-E app for the one-time use password as even if anyone find your password, they'll also need the one given by your cellphone in order to connect.