I was in the market to upgrade our old iPhone 6s's with AT&T, but ran into some roadblocks with the current promotions. I didn't want to add a line for a BOGO deal, and have no need for new services with U-Verse or Direct TV. I found an old thread on here about contacting AT&T's "Retention/Loyalty" department for possible resolutions. The end result, we were able to get two brand new iPhone X's (256gb) for $699.99 each with a 2-year commitment.
Dial 611 from your AT&T mobile service device and specifically ask for the "Retention" and or "Loyalty" department.