Hathway Cable & Datacom — calls have become a huge torture

Address:

New Delhi, Delhi, 110026

I used to hold couple of hathway connections 3 years ago in my office.. I've changed my office, city and even state. I've tried to explain them over call to remove from their crm but if no offer, i've blocked 25-30 numbers, but no use. I've tried to scold them on it, no use at all. I've even called up the customer care and tried to find out a genuine solution to this and i get the assurance everytime that i'll not get a call again.. It's almost 2-3 calls per day with a different number everytime.. Is there any way i can make them stop calling me at all?