No access to account email

Hello, i am trying to change my registered account email address from virginmedia@mycompanyname.com to myactualname@mycompanyname.com and cannot. I can log in with the username virginmedia@ as i know the password, but when i try and change the email it sends an auth code to that virginmedia@ email which i can no longer access so cannot go any further.

Oddly my monthly bills come correctly to myactualname@mycompanyname.com

Can someone help please, cant get through on the chat service.

Thank you