One thing common to bsnl broadband (Dataone) users in Bangalore or elsewhere is the frequent disconnection problem. Am not sure if this is a common problem, but I have spent countless times staring at the modem’s adsl link to appear active. Most of the time complaints fall on deaf ears. The home package of Rs. 500 for 2.5GB of use for 2mbps link is just so affordable, that I cant really think of changing the ISP.
Anyways here are the few links.
From BSNL Landline : 1504
From Other phones: 1800-424-1600 , 080 29538198