I've never seen any published deals for existing customers. This is pretty standard in the industry; Verizon is no different here.
Sometimes you can get a "customer loyalty" discount and/or a free premium movie channel by talking to a retention specialist. You can reach them by following the prompts to cancel service. It helps to know what the competition is offering.
Oh, and be polite. The folks on the other end of the phone are people just like you and me. They are more likely to help you if you're nice. Threats, screaming and cursing will end the call real fast.
Good Luck.
