BSNL Broadband — worst service since last 2 month

i am a bsnl landline customer for over 13 years in 2539 exchange in calcutta telecom dist. and i am a subscriber of bsnl broadband for over 4 years, i did not face any trouble till august 2009, but from september 2009 i couldn't work in internet because link in modem extinguished every 1/2 minute interval and my net is cut off, my telephone is also noisy. i lodged complain on almost everyday and exchange cheched my own accesories which are all in well condition, but the men in 2539 exch doesn't care to recty my connection, i also lodged complaint to area manager/ broadband/north cal tel. dist, but nobody take care about the problem. i have to bear pecunary loss for this worst service of bsnl broadbandin 2539 exch., now i am feeling helpless, i shall be ever grateful if anybody can help me to overcome this problem.