How can I find my invoice?

We had AT&T handheld with Ring Central for 6 months and never received a mailed invoice, text message, email, or got a single phone call...THEN they shut off our account with NO notice. I assumed the bill was attached to our current AT&T phone account and didn't think anything of not receiving a bill. Getting back into the account simply to get our account number was even out of the question. Jumping through hoops (& over $1000 later) we finally got our account reactivated and we are again NOT receiving invoices!!! How do I verify my account billing address, email, etc. How do I view my invoice? Has anyone else had this problem as it has cased us to reconsider going with Spectrum instead or AT&T for this service.