BSNL Bihar Circle Patna — stoppage of service and raising bills unexplained

Address:

Patna, Bihar

my land line no is[protected] was installed on 26.03.2012 later on broadband connection was also provided after 3-4 days. rs 500 installation charge and cost of modem was paid. a bill from 1.4 to 30.4 was sent totaling rs 2836 for which rs 1814 was shown as previous balance . previous balance was un explained. also connection was stopped. please explain my billing details. also change broadband plan to rs 300 pm.
kripal prasad