We traded in our old phones and received new 12's back in November. We never received our credits. Each month, we'd use the chat feature (paper trail) and the agent would say "I see everything, the credits will come next month". Finally in March, a chat agent says "We never received your old phones, so you're responsible for the full price of the new phone." I shared with them the USPS tracking info saying the items were delivered. The chat agent pushed back saying "all that shows is a box was delivered, not the contents."

I went nuclear and filed a complaint with the FCC.

Within 24 hours, I received a call from a person from the "office of the president" of ATT. I know he's not really in the office of the president, but the customer care he extended to us was second to none. He picked up the phone each time I called and gave us daily updates until the issue was resolved.

Not only did the credits properly post on the next bill, we received a one-time statement credit in the amount of the missing credits as an additional service recovery.

Long story short... if you aren't getting anywhere, file with the FCC.