Postal Life Insurance [Pli] — I want to change the nominee

Dear Sir,
This is Sushil Dharkar with policy no[protected], I have given online request for the change nominee in online via login to indiapost info pli login with hardcopies in nearby mumbai central post office, I want to change my nominees to single nominee with name: Mrs. Kanchan Dharkar, But none of the post office branches are able to help me out, I have already submitted all required documents / hardcopies to mumbai central 400008 branch, they are telling me to cancel online request of change of nomination request first, then only they can update at their end, but i have checked online but there is no way to cancel it online, again i talked to the mumbai central branch, they are telling me contact to your previous branch Bhel he hospital branch bhoapl but i can not contact them as none of contact no is working for (HE hospital bhopal) I am posted to Mumbai now, i already talked to the customer care but they are telling that even they cannot cancel it.
I just want to change the nominee, thats it, why they cannot change it online or why they give the option for request to change nominee online, if they cannot approve it.
My Postal Req ids are
CPCON[protected], CPCON[protected],
CPCON[protected]
all are related to nominee change.