Rs.38000 bill for 3 GB of data consumption from TATA Docomo

Hi, I was a customer of TATA Docomo for 2 years. I always paid the postpaid bill prompt at time. In the month of June 2014,after getting a customer care call from TATA Docomo about the 3G plan, I activated the 1GB 3G plan. The plan is as below: till 1GB it is 125 Rs after 1GB till first 30 MB it is 1p/1kb after 1GB + first 30 MB it is 1p/10kb. With this, I activated the plan and I consumed 5.0184 GB of data on June 19,20,21.My Bill cycle is 20th to 19th of next month.So the data consumption is divided in to two bills.With the plan I have over consumed around 3GB data(5GB-2GB plan data). With the above mentioned plan the bill amount should come around Rs-3000/-. But the bill was miscalculated and I got a bill for Rs.38,180/-. The bill was charged as 1p/1kb for the entire data and hence the bill amount was amplified as high as 10 times. I have called the customer care and after so many calls and mails they accepted the issue and they waived of the bill for the June month(the data consumed on 19) in August month bill,but they did not do it for July month(20,21 June). I have attached the proof of the conversation that i made with the customer care person which will give fair details about the above DATA Plan. After that I raised two complaints 422037487 ,420537473.The complains was not resolved and my phone number was barred. Whenever I get mail from TATA docomo, I have replied the mail to resolve the issue and also called the contact person (mentioned in the mail) to resolve the issue but of no use. Today I got a call from a person called RANGANTH claimed himself as a legal adviser of TATA Docomo from this number [deleted]. He threatened me by saying the following. 1)I will be be tried as a terrorist since i didn't update the new house address to TATA Docomo. 2)They will create problem for my family members. 3)A FIR will be registered and that will be mentioned in my Passport. I have the call recording for the same and I can produce if want. Also got a call claiming as local Sub Inspecter and he threatened to pay the money otherwise face consequences. Before the issue happened,I was using that number for 2 years and I have never defaulted any payment for even a single time.I just didn't pay this bill because there is a blunder miscalculation from TATA Docomo and the amount they charged is Rs.38000/- for 3GB of data. For the past few years I have got so many mails calls from TATA Docomo and i was mentally harassed and tortured too much for just being a customer of TATA Docomo. Now I want to put a case on TATA Docomo for all the mental harassment. Please advise me if i can file a case against them and the chance of wiiing the case. I have all the call recordings and Mail chains as proof.