Taking money from a deceased account after the death

My father died on 13th October 2023. In this situation on 14th October, I have transferred maximum money to my Bank account using net banking. on 25th I have informed the Bank for my father sad demise and in that branch my father`s pension account is exists jointly with my mother. After completion of all rituals my mother visit to bank and ask about withdraw money from joint account but bank denied and freeze the Joint account. After that I have complain in National grievance Portal with the details of such freeze by bank of joint account. After the complain the branch manager reopen the Joint account to my mother for operate the account. After 2 days the bank manager call my mother and ask why the fund is transferred by me after the death of father and accused me as a fraud and advised to deposit the same through cheque. Also issued an email and asked reason for such activity. Me and my mother is only legal heir and my mother never complained against me in the bank. I have reply the manager as there was fund crisis and that situation no other way to collect the fund so I have use the credential of net banking and request him to treat it as family loan and next day a cheque with a same explanation letter had deposited by my mother on behalf of me . It was near about 2 months passed but manager not solve the problem and all-time accused me and he convey that due to my complain bank took the matter as a sub-judicial case and it will take time to solve. Now I want to know, when I have deposited the cheque, Death certificate, Legal heir certificate issued by municipal authority and my mother have not complain against me and the case also not directly related to the complain lodge in national portal by me. Then why bank manager not solving the matter till date? What am I do in next? Is there any legal case can be suit on me by Bank?