Need to file a complaint with corporate

I need to file a complaint with corporate.  I have spent the past 3 months trying to fix my account,  however, the customer service line will not let me escalate the issue to the next level.   As of now, my services have been disconnected even though we entered into an installment agreement in June.  For some reason that did not work so the system let us do it again in July.  Each time we paid the $50 fee.  I have had to call customer service at least 2 to 3 times a week to have my service restored bc the system kept disconnecting our services while the installment plan was processing.  The last time I called inwas told that they could not put the installment plan in place because "we didn't meet criteria".  I asked what criteria and I was told it did not matter bc we didn't meet criteria.  I told them that I have screenshots of the confirmation page of the installment agreement in July.   They told us to "reply to the last confirmation email that was sent to us and attach the screenshots and other information we have and someone will take a look at it" However, it specifically states in the email that it's auto generated and that we cannot reply to that email address because it is not monitored. They also refused to restore services in the meantime.  They refused to look into it further.  My only option after this would be to contact my state AGs office and the FCC and file complaints