Sirius XM Radio Auto renewed a subscription without consent. Internet

In September 2012 I called SiriusXM to cancel my service.  Their customer service department told me they were changing the way they operated and if I gave them another chance they would discount my fees for 5 months so that I could see if I liked their change.  I told them I would stay for the 5 months but they were not to auto charge nor auto renew my account unless I contacted them.  They did not change their format, I changed to different radio services. Unbeknownst to me they auto renewed my account but instead of charging my credit card they started sending me paper bills.I called them and told them to cancel my service, they told me it was canceled but that I had a accrued service fees that I owe them ($37.15).  I explained to the customer service representative that they were not supposed to auto renew my account and I was assured that they would zero out my balance.  About a month later they sent me a new bill with the same balance on it.  Again I called and was assured that they would remove the balance. And here it is about another month later (today April 16, 2013) and I received a new bill with the same balance on it but when I called them this time they gave me a balance of over $42 that I owe them and was told they would not zero out the account. Every time until today I would get someone on the phone that would be sympathetic and assure they understand and then do absolutely nothing but send more bills.