Yeah, that'll work. Call.
Just say "Dish has some pretty good deals, and I'm thinking about cancelling. What are you going to give me for free to keep me as a customer?"
This is not sarcasm. They'll throw all kind of crap at you to keep you on.
That said, I'm with Dish and won't ever go back to those scum-sucking morons at Direct. I hate their customer service. Want some free stuff and get treated like trash? Direct's the way to go.