Net Flix Charged for services after cancellation phoenix, Arizona

I received a 6 month subscription to Net Flix as a gift.  Prior to the end of the 6 months, I cancelled the subscription.  I assumed that would take care of it.  I did not notice until 7 months later that they had been charging me every month.  When confronted they said they would credit me for the last month but no more.  Escalating up only led to same answers.  I have confirmation emails that they cancelled the account.  Follow up emails asking me to sign up again. How can they collect for something I did not order ?  they admit there was a mistake somewhere but declined to reimburse me.  Pretty crappy customer service.