trouble blocking numbers from Android app

I figured out that if I have already assigned a contact name to a number, I can't block it using the Android app. I don't like this because I freely tag dubious numbers with contact names like "D Craply", but use actually blocking very sparingly because it involves falsehood. I can block D Craply by logging into the web site. I long for the day when a blocking option not involving falsehood is offered.