They advertise family plan with data plan and text for a reasonable price. After you sign up, they bill you an amount that is not agreed upon. A closer look at the billing statement, you will realize you are paying access fee to the family plan per line. It's like you buy a house with a driveway but you need to pay at the gate in order to use the driveway to get to your house.
This access fee is not nominal. It easily racks up if you have multiple lines.
Also, in the billing statement, you will be charged additional fee that they claim government fee. If you look carefully, you are paying for their main office that generates the billing regardless of paperless (online statement) or paper statement. In other words, you are paying the tax AT&T is required to pay the government for them.
Bottom line, if you set up automatic payment that you believe helps in reducing the payment per their advertisement, you are still required to monitor each payment; AT&T will start adding hidden fees or something to increase your bill back to where you used to pay before (an arm and a leg).