Loan given against Joint fixed deposits without consent from joint acc

My husband made four fixed deposits in SBI of 10 lacs each with me as a joint account holder after completing all the formalities & documentation. All original FDRs are with me in physical form. Later he left me & moved to another city, stoped all my expenses without a divorce. After about six months he took about 29 lacs loan against these FDRs without my knowledge. When I approached bank, they informed me that my husband removed me as a joint account holder & made me a nominee. At no stage bank took my consent or even informed me about all this. Later my husband died from Covid. My question is whether bank had authority to change my status from a joint account holder to a nominee and later give a loan against these FDs without my written consent. I have branch manager’s letter where he has accepted that I am the joint account holder in these fixed deposits. What legal action can be taken against the bank.