I used to work at att, I had 0 ability to tell you what your actual bill would be, more like a +-10$ estimate. Often times people's bills would slightly change every month by a buck or two up and down, no idea why.
I left directv because of this some years ago. Every month the bill was just slightly different. The person who called me begging me to come back insisted that wasn't true. lol
Literally nothing in any of our documentation mentioned it all, and it wasn't everyone. Always just makes as generic things like fees. They were lying or new
