Hathway Cable & Datacom — legal notice for modem submission

Address: Kadbeesanahalli, 560103

Hi,
My hathaway account no is [protected]. I was using hathaway prepaid broadband till 2019 in bangalore. I switched job and moved to a different city. The internet connection was disconnected.in jan 2018 i got legal to submit modem or pay fine. Now i am in different city and the modem was collected by the local hathaway dealer/vendor later on but i guess he never updated the authorities. Now i am getting calls regarding legal notice for return of modem. Why?
There is no proper contact details of the concerned department to resolve this issue. It's total harassment on the company's part. 1st of all no proper process no proper information and no contact for resolution but out of blue you just get a legal notice served on email. Is this why people avail service, to be harassed? Is this the company motto?
Still till date i have not been able to resolve it.