You can block the number depending on what type of phone you have. I know for a fact that the LG Chocolate will do that, but I don't know of any others. I actually had the same problem and Verizon told me that all they could do was to change my number for free. Depends on how frequently they call you, too. you could dial the number back, but just put *67 in front of it to show "unavailable on their phone as well to figure out who it is, just pretend to be a political party!
