Harassment and defamation

Dear Sir, As above mentioned subject, I was using idea postpaid number 9011262400, stopped its use in march ,bill due was 2400, I couldn't pay it due some financial reasons, On 12th July I got call from 8826301273 this number, near about 11am to 12pm . Person ( Mathur) on call told me ,he was speaking from shivaji nagar pune court, later he said he is going to file case against me in charge of fraud with company, then said if wanna avoid this matter, I must pay within an hour, I agreed but due to financial problems I requested him I pay 1500rs now and remaining amount on next months first week,he denied and said Aaukat nahi to postpaid Ku use karte ho, I said file case I will go by law. Later he started series of calls to my relatives, colleagues,and friends , told them I have done fraud with company and he is going to lodge complaint against me. Company done my social and mental harassment, defamed me in my social n private life. How can company use my private contacts without any legal permission of higher authority. I have call records done to my friends Can I file a case against Company in charge of harassment and defamation