NFL Sunday Ticket Refund

I was charged one month prior for NFL Sunday Ticket $65.99 so I cancelled it before it started.  I was told to pay it and that I would get a credit on next month's bill.  It has been four months and still no credit.  I have called 7 separate times and all of them said the credit will be on next month's bill.  I called again today and they said I was never charged for it.  The reviewed my bill and it shows no charge whereas my bill said it was charged.  They will not provide me with an address or email address to send them the paper bill I have showing the charge.  Where are they located so that I can personally bring them the my copy of the bill for I think they deliberately deleted it from their system to prevent giving me the credit.