Hathway Hyderabad - account not closed and they are threatening for legal and demanding money again and again

I am not using hathway since * or * months because they are not providing service in my new area. they called me in January **** and asked to pay the penalty otherwise i could face legal notice. I paid and they promised to close my account. But they cheated me and they recharged my account for Jan ****. they did not come to pick up the device. next month they again called and demanded money. I refused and asked them to collect the device but they did not come and instead, they continued calling me and threatening me and demanding money. My work is getting affected because they call us any time even if I am working. I emailed them, tweeted them but no response. Now they are asking me to pay *k or else I i will face legal notice. Please help me.