My sister and my son had joint locker in Union Bank after death of my Sister my son continuatined J

My sister and my son had joint locker in Union Bank after death of my Sister my son continuatined JOINT account adding his wife.My sister executed will deed in my favor to claim My mother's and sister's Gold ornaments and property documents. nMy is not handing over orginal saledeed copies and Gold ornaments, as he himself continuatined as grand son ignoring me as legal heir and also having will.The Union Bank silent over the issue even after submitting the will and also legal heir. IMMEDIATE after death of my Sister he in possession of said documents and Gold ornaments and Australia for longer time.As per the death claim settlements of Union Bank Rules failed by Bank no inventory of such situation immediate after her death.Can I proceed further with Bank by serving Legal Notice Civil and Criminal action having neglected the Bank Rules and Regulations.