Messages sent through imessage uses the data plan and won't be caught by the Verizon Wireless block.
I would suggest turning off imessage on your phone. This will force all messages to go through the Verizon Wireless network. You might need to adjust your message plan size if necessary.
I don't know if it possible to block someone from sending you an imessage.
If I turn off iMessage and the person sends me a text, will they receive some sort of message back saying they were blocked so they know and can take a hint? The reason I ask is because I use iMessage regularly and don't want to leave it off all the time because of this. I'd like to leave it off for a few days so they get the picture.
Delete the person from your contacts, then go into your Settings-- Notifications-- Messages. At the bottom of this screen, change your option from Everyone to My Contacts Only under the Show iMessage Alerts From option. This will not allow that person to send you an iMessage. They should receive failure notices on their texts, should they try that option.
That's actually incorrect. It just turns off alerts. Messages will still come through.