Received bill 12 times of the plan and more than 3 times the credit limit.

Location/place: House number- 14-1-211/480, Parwath Nagar, Allapoor, Borabanda, Hyderabad, AP- 500018

Name of company/service: Tata Docomo

I bought a Tata Photon Plus in June 2012 with a plan of Rs 250 and credit limit of Rs 800. I received a letter from Tata Docomo stating the same on 5th June 2012.
I was surprised to see the bill when it arrived on 5th July with a total of Rs 2,925.85.
I have called the Tata customer care and are logged a complain. Since then no one contacted me for almost 10 days. Then i started receiving calls from them asking for payment. I told them that how they can send me a bill of Rs 2,925.85 where my credit limit is mere Rs 800.
Since then i have received a number of calls, they have always abusive language which is never acceptable.
After almost 3 months I received a call from a lady named Sonali from +919880143478 stating she is calling from Mumbai court. When i checked in Google I found that the number belongs to Karnataka. I informed her that I did not receive any notification or about the complaint which I made. She start using very abusive words.
Sir/Mam,
I am very tensionised with the attitude of the company. On 25th January 2013 I received a call from +918459057794 stating that they sent 2 notices to me. However, I did not receive any notice. He also used very bad language. Please help me as I do not want to get more tension.
Details:-
The first letter received from them on 5th June:-
Relationship number- 913721675
Second letter received from them on 5th July:-
Acc no.- 913721675
VLCC_-202-20501
Bill number- 1262595154
Tata Docomo number- 09246482263

Thanks and regards,
Siddhartha Rao
+919160002786