AT&T refuses to cancel my small business account. Please Help!

I have been an AT&T Small Business Customer since 2005. I recently found out AT&T has been over-billing me for years (charging me for 2 DSL lines when I only had one). I've called 4 separate times to have this corrected. Each time the agent (at a non-US based call center) has told me they would correct it. Each time I recorded the agents name and ID number. I asked for a confirmation number on each call and I was told they do not provide them.

After tiring of the runaround, I decided to switch providers. I contacted AT&T to reconfirm I was not under a contract or obligation of any kind, which the representative confirmed. So I called on 03/30/2015 to cancel my small business account IN FULL. Again, the representative assured me the order was placed for the cancel/disconnect.

Unsurprisingly, the cancel/disconnect did not take place. I received a new bill for the service time of 04/07/2015 to 05/07/2015. So instead of getting a final bill for 03/07/2015 to 03/30/2015 with a partial credit for March 30 to April 7, I now have another month's worth of service that I'm being billed for and not using. And AT&T's policy is that I cannot speak with a representative or make changes to my account unless it is current.

Based on AT&T customer support's previous history, I can clearly see the likely future pattern:

1. Cancel account

2. Account cancellation does NOT occur

3. New month's bill generated

4. Must pay for ANOTHER month's service just to have the privilege to speak with a customer service representative again

5. Start over at step 1 and repeat on an infinite loop.

Again, I've recorded the date, time, customer service representative's name, their Agent ID number and the nature of the communication to no avail. When I provide this information on the next customer service call the only response I get goes something like, "Sorry, they didn't put the order in. I will do that for you now." If I ask to speak with a manager, they either flat out tell me "No" or the connection is lost.

I'm at a loss. This is beyond surreal. It has literally become some type of dystopian nightmare. Any advice or suggestions would be greatly appreciated.