Here's what I did this year so try this: Call back and tell them you are canceling. Get transferred to Retention and tell them you want to cancel but schedule the cancellation for two weeks out. If you talk to a different rep in Retention you may get some better offers, for some reason different reps seem to offer different discounts, but if you don't get what you want then stick to setting up a cancellation date around the end of the month. Once they put you in their system as definitely cancelling the service, then more discounts magically open up for you. You may or may not get and email within a few days saying something to the effect 'We heard you are canceling, we want you back' and listing some discounts including Sunday Ticket. Regardless of whether or not you get the email, in a few days you can call back, go to Retention, and mention to them you got an email wanting you back and they should be ready to wheel and deal.
Doing this I got: $45 off a month for 12 months. Sunday Ticket Max for free. All movie channels free for 3 months. $200 gift card. YMMV
5th year getting Sunday ticket for free.