Hathway Cable & Datacom — not terminating my service

Address:

Mumbai City, Maharashtra, 400005

I was using hathway internet service in colaba, mumbai.
In march 2019, i shifted to another flat and requested hathway to shift my connection to the new address. The hathway representative told me that they could not provide services for the changed society (In same locality).
Therefore i requested them to terminate my account and refund my security deposit.
To my utter inconvenience, hathway refused to do so and they have been pestering me with numerous calls (More than 100) asking me to renew my connection.
When i politely told them that i have moved to another location and i need to close my old account they still refuse to do so.
Please help me stop this pesky calls from hathway.