Verizon allows me to block up to 20 calls, but sometimes that isn't enough. I pay $5 extra per month for the privilege. When I get excess robocalls, I simply add them to my contact list and set the ring tone to "no ring". It's not perfect since I still hear my phone identifying the number, but at least it won't ring.
These robocallers should realize that they're wasting their time with most people, since who'd want to buy a product from such a rude and intrusive company. But then, I guess there are enough gullible people out there who make the robocaller's time worthwhile. :h