Bank forgery

My brother withdrawn huge money through NEFT,fund transfer,cash withdrawals from my parents bank account after their death.i m the nominee in both account.Bank verified by calling over customers mobile number registered with bank when NEFT were being done.Even then account debited.My brother withdrawn huge amount from my mothers' pension account through ATM withdrawals even after her death ,till one year after her death...when i came to know this i submitted my parents death ceritificates with my kyc and written request given to bank to freeze the accounts ....and bank provided me all the docs (photo cppy of chqs,neft form) which are seem to be forged ,signature mismatched...bank advised my brother to redeposit over pension amount...he did so...but i didnt' get any amount ....what should i do.. is this punishable? Pls mention sections as well.