Un-necessary calls

Location/place: Pune

Name of company/service: Videocon D2H

I am not a Videocon D2h customer. But my mobile number was previously being used by some Mr.Tukaram, so its registered with them.
I keep constantly getting calls and messages from their center, in-spite of telling them to remove my mobile number from their database as I am not their customer.
Every time their caller promises that I wont get calls, but no use as i keep getting their unnecessary calls.