Farud case by tikona or may be threats call

Hey I have already disconnected my tikona connection prior 10 days of expiration and also returned all the material to their engineers. Now after almost when i forgot everything one advocate calls me tells me he is from tikona and claims that I haven't paid due to tikona. I have all the call recording and other records of the customer executive and disconnection time. As TRAI has regulation that we should cancel the plan seven days prior i have done 10 days prior and even their executive told me that i dont have any bill pending, still tikona is threatening me through advocate calls and saying that i have to visit Mumbai and if i fails i have to pay 45000 fine . As a student i neither cant visit mumbai for a false case nor i can pay 45000. I tried calling tikona but they have no response. What should i do now? If someone can help it will be appreciable as i have already seen many thread of the same topic. And last my question is this that how a company with so many fraud is still running in this country.