I work for company where add-on was created (as unpublished, just for signing purposes, being updated from our servers) couple years ago under private account of the person who created it and than left company. Now we need to get to this account, but problem is that we are unable to log in there. Even person who originally created account cannot log in. We tried password recovery procedure on https://accounts.firefox.com, but it says account does not exist.
What else we can try?