Tikona — Getting threatening calls to sue for not paying bills

I bought a tikona broadband connection with 6 months validity. When the 6 months are completed i wanted to change my plan from 6 months to 1 month as i was planning to shift my home. But apparently their website and mobile application are not capable enough to change my plan which is why i have called customer care regarding the same but no answer on that. I sent one email stating that i want to change my plan from current but there also no reply. After that i added in that mail only that if this plan continues without my permission i will not be responsible for any charges. They should have disconnected the service but they wanted to get illegal money from our pockets so they haven't disconnected the connection. Now i am getting calls from a so called lawyer but from her talking manners she is is just like a recovery agent only (No professionalism). She told me its not upto her that she can disconnect the connection. So why should i be one to pay if tikona has not disconnected the service if no payment or no confirmation is there.