Tikona Broadband Company - Unfair billing and extortion calls

I have been a customer of tikona from ** Jan to **th March ****. My three months plan which was prepaid was about to expire on **th April but I had to end up this service due to poor and hassle connectivity issues on **th March. Even after dismantling connection request the executives tried hard that I don't leave their service and they continued to generate monthly plan bills for my user id. When I did not respond to them, they hired a person called Amit Kumar in the legal department to threaten me and to make extortion calls. The person used very abusive language and tried to scare me about legal proceedings. He called me from around ** different numbers to threat. I told him that I'd complain in the police he said go ahead. I want to know that when there were no outstanding charges were pending from my side then why should I pay a single penny to them. My complaint is just to take legal action against tikona company who distributes customer numbers to the third party for extortion. There are so many complaints against this broadband service.