Thank you for your post!
Our Gas account was in my name (Wendy). We transferred our Electricity to AGL. My husband has a pension card so we needed to have both accounts in his name (Phil). The Gas and Electricity are now in my Husband's name. The old Gas bill shows a credit of 1 cent and we are using the same email address so I cannot access our new accounts because my old account keeps wanting me to login.
I wrote this post after a long phone call where I had trouble getting the person to understand what I was talking about and when the call was finished nothing had been fixed. After posting I got onto online chat and thankfully found someone who looked into the account and understood what was going on. They told me that the account was closed and re-established under the new name but to give it time to update just to make sure (this gave me confidence as it is exactly what I would expect to be told when it comes to online accounts).
Everything is now how it should be and I can now pay my 2 bills.
Thank you, Angelina(?).
To PhilWendy's point, only one primary name can appear on an AGL bill. However, your flatmate can be added as a contact person (you can do this using your AGL My Account) so that they can contact AGL on your behalf concerning the account.