Hathway — Harassment by repeated calling

Address:

Iyypanthangal, Chennai 600056

I live in Chennai. I have disconnected the hathway broadband. I have called to customer care to stop the service but almost everyday i'm getting call from hathway stating that we're providing offer please do recharge or take reconnection. How to stop this call? Even though I block the number they keep calling from different numbers. Please help me to stop this harassment