Mtnl dolphin mobile service
False bill

I am a regular user of MTNL Dolphin postpaid connection . about four months back i recieved a bill amouting to rs 3000, wherein it showed that about an amount of 2600 had been used on ISD, when confirmed with the telephone department, they said that my connection did not have the isd facility . however, my connection was barred after four days .after 6 days i recived another sms that my bill was 6000 now . my connection has been barred ever since an inspite of my repeated efforts, the department is not ready to comment . at present my connection has been barred ever since and i have suffred enormous loss of my business due to the phone disconnection . kindly suggest me what to do.