BSNL Customer Service Centers (CSCs) which is open on all seven days from 8.00 AM to 8.00 PM is very effective. For BSNL Broadband you can call 1800-424-1600 (toll-free) and register your complain.
They normally resolve the issue on the same day (in my case they came home at 6:00 in the evening to resolve the issue). Its better then calling the BSNL office.