The next time you get the mail ads, and in that envelope is a postage paid return envelope, fill it to the brim with junk, and mail it back. They will have to pay extra postage. May not get them off your back but you'll feel better.
I have Verizon for my landline and cellphone service. Have Time-Warner for cable TV and Roadrunner for internet. I am happy with the latter two, and am reevaluating my Verizon services (I get liberated from my cellphone contract in October).
I originally was going to use Verizon DSL -- that led to 2 weeks of telephone he**, including "tech support" from script readers who could barely speak English, and a garbled landline. I told them (politely) what they could do with their DSL, got a self-install RR kit, and haven't looked back.
Verizon has been inundating me with snail-mail (2 or more messages a week) promoting their DSL and/or Fios "service". I have no interest in changing (have done very well with TWCNYC/RR, and have no desire to lose out on cable-only NY1 - one of my favorite stations). Verizon must have destroyed several trees to provide me with all this direct mail, which goes directly to my shred pile. Their website shows no option to discontinue this onslaught.
What do I have to do to get Verizon to stuff it? They are not going to wear me down by this constant pounding; they make me think more and more about ditching them entirely.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic