Central Bank Of India — family pension is not getting pension after 4 years of death of pensioner

Dear sir,
My father late. Mr h. M. L. Bhatnagar was retired from railways, having ac no - [protected], at aminabad branch, lucknow and expired on 23.12.2014. I had informed to bank and requested for start family pension for my mother. As per bank advised i had opened an account of my mother in same branch with ac no - [protected].
But that branch manager said that they dont have the latest ppo of my father and pension will start after submitting that.
I had applied for the same at drm office lucknow and they said it will take 2-3 month time and will directly send to central bank.
After so many visits to that branch and requests, at last bank has started a minimum pension of rs 11016/- on 03.04.2017. And said this is a min pension which they can start but for actual pension and the pension amount from 23.12.2014 to 02.04.2017 will give you by our head office.
But after a span of four years we are nither getting any responce from your bank nor getting the actual pension and balance amount.

Please help me in this case that, who is the concern person and what is his mail id or phone no.
I am herewith attached the below mention reference docs for your kind notice...
1- death certificate of mr h. M. L. Bhatnagar
2- ppo of mr h. M. L. Bhatnagar
3- service certificate of mr h. M. L. Bhatnagar
4- bank passbook of mr. H. M. L. Bhatnagar
5- bank passbook of family pensioner mrs pushpa bhatnagar
6- bank letter.

Seeking for your kind support.

Thanks & regards
Vishal bhatnagar
Mob no - [protected]