How to block a blocked number on iphone?

They keep saying mean things i don't know who it is

Added (1). They are also saying they are going to stab me and i'm only a kid i think they are too

Contact your iPhone Service provider. If the sender is using the same service, the sender can be blocked. If they can't be blocked, you will have to take further actions legaly.

1. If the number's blocked, don't answer it.
2. If it continues, call your phone service provider and ask them what to do.