Bigamy by wife

Dear respected sir/madam I am fighting multiple cases and paying maintenance to my wife for last 4 to 5 years. I got to know she is been married for last 3 years and having child from new marrige though our divorce is pending. In my personal capacity i got to know her new bank account no in axis bank where she uses her new surname. My question is how to get the document from the axis bank about her application form and kyc papers submitted into the bank. Does RTI applied in private banks? If not what else I can do where axis bank can't deny me to give the documents.