RBL Bank — repeated calls from rbl inspite of dnd

I have activated dnd with my mobile service provider but still i get calls from rbl bank.
I have time and again mentioned to all callers from rbl bank that i am not interested in availing any of their services and also that i do not want to receive any calls.

Just last week they apologized and said they would add me to their dnd list and today i get a recorded call.

I keep blocking their numbers but they call from new numbers repeatedly.

This is plain harassment.