ATT Long Distance Legacy Can't Find My Old Unused Account, Yet keeps Billing me Carol Stream, Illinois

We had a long distance account with ATT probably five years ago.  We no longer have this long distance number or the ATT account & haven't for years. Recently we started receiving bills for this account which include a charge for "minimum usage & taxes" which total $2.14/ month.

I called to let them know we don't have the number anymore or the account.  After two+ hours on the phone & being transferred to 20 or more people I got nowhere.  They can't find our account on record using our old phone number, business name, or the BIN number on the bill (there is only a BIN number not an account number) After that exhaustive call I tried using the online customer service chat but they only redirected me to the number I had already called. 

Finally I just stuck a letter in the mail with my bill explaining what I had been through & for them to close the account etc.  I haven't heard back on that. I called again (always calling the number on my bill).  Again, no record of my account at all. They had me fax in my bill.  They said it was an old "Legacy" Account & told me to call the number on my bill... I told them that's how I was talking to them.  So they transferred me to I don't know where & when that number rang through I only got a message that they were closed & to call during normal business hours.  Too bad it didn't tell me when those hours were or the number I was calling. 

No idea where to go from here.  I'm up to a whopping $8.72 on my "account that doesn't exist".