I'm listing this as YMMV because I'm not sure if this will work for everyone but here's my story.
I was upset that AT&T raised my subscription by $10/month AND dropped the NFL network so I was planning to cancel this evening. When I went to "Manage my subscription" and clicked "I want to cancel" the next screen offered a $15/month discount for 2 months if I stayed with DirecTV Now.
I am a day one subscriber so I was getting the "Go Big" package + HBO for $45/month. After the $10 price increase and the $15 discount I'm currently paying $40/month for the next 2 months.