I found this in my Bank of America account. YMMV and amount might differ:
Earn $75 cash back when you make two transactions with AT&T wireless using your eligible card associated with this offer.
Offer expires 6/19/2017. Must make two separate transactions with AT&T on wireless products or services of at least $15.00 on the card associated with this offer by 8/3/2017. Your $75 cash back is earned within 30 days after making your second transaction. See offer details. Taxes, fees, other charges & restrictions may apply. Add'l speed, usage, and other restrictions apply. See plan details. Offer valid one time only.
This looks similar to last year's deal:
This is a potential $45 moneymaker. Last year, members have reported even cell phone top-ups on att.com worked. Check the full thread for more examples.