Directv AT&T Deceptive trade practices, offer no hassle free trial, start charging without permission, refuse refund Nationwide

I've been a directv customer since 2004. In 2014, during my call to directv to upgrade my equipments, they offer me a "no hassle free trial" of their movie channel package. The customer rep stated they will offer me 6 months free trail of either showtime channel or Stars channel. I response as "no thanks, since I don't want them to start billing me after the "free trial" or commit to any terms. The rep reassured me that this is a "no hassle trial" that when the trials ended, the channel will stop automatically and I will have to call in to subscribe to the channel. Due to that reason, I agree to accept the offer. I watch the channel for a month or so and since the movies are old and repetitive, I stop watching the channel and thinking it will simply fall off as the CSR rep claimed. I since have completely forgot about this. Recently, I notice an increase of my bill and when I pay close attention to it, I saw they have been billing me with the "showtime channel" since Jan 2015 and when I called to confront them via phone and request a refund of this "deceptive trade practices".. they said they can only refund 2 months of charges instead of 15 months that they charged me. They then said I can cancel my service but will be subject to an early termination fee.