You have a fantastic phone, joy3141. I double checked features for the iPhone 5 and confirmed there's not a way to block messages from a specific contact without blocking calls too. Our Call & Message Blocking http://vz.to/MqEgqB is a great way to block unwanted contact from specific numbers, but it would block both calls & messages. If your dad is on your account and you're hoping to block all of his text messages to or from anyone, there is a text message block available at www.vzw.com/serviceblocks you can add to his line.
Please follow us on Twitter @vzwsupport