Hello @billyt!
Using myATT either online or via app is one of the easiest ways to manage your account no matter where you are! I will be more than happy to help fix this issue!
Have you registered the business account yet? If not, please visit our small business account page to get it set up. You will need to input either your account or phone number in order to get started. Here is a great link which has guides and information on business accounts, and how to set up myATT for them.
Please let us know if you have any other questions or concerns. Have a fantastic day!
Katherine, AT&T Community Specialist