Outlook.com hacked, Changing password doesn’t get them out.

Question

Someone has hacked my Outlook.com and changing my password doesn’t help to get them out. When I go back they still there. When I try and click on their Microsoft profile it says account doesn’t exist. They are also into my OneDrive. When I view the file path of folders on my Mac, instead of saying OneDrive in the path it says something else and refers to d.docs or something. Getting help from Microsoft seems to be impossible. I just get passed on from one person to the next. Can someone please help me resolve this? Thank you.