Bank's reluctance in releasing my gold

I am a software engineer and I live in USA. My father is an Account holder of AndhraBank, Kapra-sainikpuri branch. My father took gold loan using mine and my wife’s jewelry after my wedding in 2017 through his account and I was the nominee. Unfortunately my father passed away on 11th April 2018 due to cardiac arrest. I paid the bank complete gold loan amount when it was due after my father’s demise and when I wanted to relieve all my gold, bank is not releasing my gold on some pretext. They now say that they didn’t register nominee name on paper for the gold loan that my father took on my behalf when he was alive. It is the bank’s failure that they did not register nominee name on paper for gold loan and apparently I am the nominee for my father’s SB account. I explained the facts and circumstances to the branch manager and assured them that I will take full responsibility and give complete security for the gold after it is released to me. I am not able to get my own gold from the bank