at&t Ripoff

I called at&t to dispute a charge for a voicemail service called "jungle mail". I explained that I had not authorized and did not want this service. I was informed that I would have to contact the company because at&t could not stop charging me for this service even though I did not order it. I called the company and told them that I had not ordered the service and to stop it immediately. I received my next bill from at&t and the original change of $26.68 is still there and now there is a $12.95 monthly fee being charged. This is a total ripoff. I was told by at&t that the only way I can stop the change is to turn off my lineline phone. How can someone add a service to my account and then I am required to pay it or give up my phone. Do I not have any other recourse? I've had this phone for years,always paying my bill and would hate to have to change it.