Blocked Contact can still text me
I blocked a NON apple user phone number, so they do not have an Apple ID, yet they are still able to text me. Any ideas?
I am not sure how did you block it. If you have used the correct process they can not send an SMS to you ever.
Block messages from a specific person or number
In a Messages conversation, tap the name or number at the top of the conversation.Tap the info button, scroll down, then tap Block this Caller.
Block, filter, and report messages on iPhone - Apple Support (IN)