Hathaway Broadband Bengaluru - Non stop calling and threatening me that they re going to file a case against me

I had gotten Hathaway broadband connection in April month of **** and by first week of October I had let them know that I'd be leaving Bangalore next month and I won't be continuing the connection and that they cut my connection then on. They said okay fine and when will you be coming back I said I won't be my college is done so I'm going back to hometown and they said okay to everything so I left it. Few days after that some other agent calls me and asks to recharge and I tell them the same thing, and next day a new agent calls it continued for a few weeks until I got angry and blasted at them, asking then to take off my name from their calling list since I've already asked them to cut my connection and then they said okay sir the calls won't come again. They didn't call for few days but again they started calling multiple times in a day and I told them again and again that I'm leaving cut my connection they did not and continued to call me every day. I left banglore by the end of October **** and they're calling me when I'm in Kerala now and every time I tell them the same thing I'm not in Bangalore I'm not in Bangalore but to no avail they continue to call me for weeks and then one day I contact a senior level representative of the company and she tells me sorry and that we'll send someone to collect the router and it's done. It's been month and a half or * months since I left the flat owner gave to room to someone else and idk what they might have done with the router so I told them I don't know if the router will be there. I told you may go there and I'll ask the landlord if he can go check and when he checked he couldn't find any router there as they've cleaned, repainted and given the room to someone else. I told them that if you had to take the router you could've asked me to return it earlier when I was banglore now all of sudden after a month and half of me telling you cut my connection you're asking me to give you the router. And to this day they are still calling the more numbers I block the more calls I get from different numbers and some automated calls that say I've to pay ****rs or they'll file a case against me and so on. This happened when I was in college and living in SG Palya Bangalore.