Tata Sky — promotional calls

I am registered for dnd for my mobile number. I am getting too many calls from random mobile numbers for tata sky sale offer. I understand these calls are from some agency. But these callers are untrained #. I don't want to receive any such calls.

Every time i block number, i get calls from a different number. And these callers disconnect the call as soon as i mention about this trouble.

These # are spoiling tata sky's reputation. If these calls don't stop. I will make it sure that i mention this on all the social networking pages of tata sky.