This can be a website or server issue, it's better if you contact their reps via chat, I always get positive results there. Just go to this link http://vzw.com/contactus locate chat and then select "Managing my account" tell them you need to block a number on your line, it will take them just 5 minutes
You can even block up to 5 numbers each line hehe, hope this helps!
How are you trying block the numbers? Are you using the MyVerizon application on the phone or are you signing into your MyVerizon account online with a computer?
There was another thread recently on this community forum, where the customer couldn't block a number using the application, but could through a computer.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.