If they don't want to give to you, just cancel the service and wait until they call back, usually the following day.Damn, that is a pretty good deal. I call every few months and threaten to cancel and I don't get anywhere near that good a deal... though I do have more channels.
My experience the call back folks are way more flexible than just calling first and asking to lower your bill.
At the end of the day is better have something than nothing and DTV is willing to work once they see you are serious about leaving them.