Bharat Sanchar Nigam [BSNL] — from bsnl, i am unable to make or receive calls and i am unable to receive messages

Address:

Alps Estate, kaikondrahalli, opposite to fire station, 560103

I am using bsnl as my secondary sim. It is linked to all my bank accounts.
Most of the time i see zero signal or weak signal.
Sometimes i am unable to even get otp related to banking due to zero service.

I somehow gave a complaint before few months (Their complaint portal mostly doesnot work till the last step).

Even now i am unable to call their 1503 customer care number (Due to poor network signal and my primary sim doesnot call that number 1503) or register a complaint in their site.
Requesting immediate resolution.

Is somebody could direct me towards a working way of resolving this issue, i will be grateful!