Contact your bank immediately after finding that funds have been transferred from your account without your consent. The bank will then take notice of your claims and immediately freeze the account. You will not be able to make any more transactions. The process of finding the person accountable for unauthorized transactions starts here.
Get a print out of your bank statements and check if any illegal transactions were carried out. You may require going through details dating several months back. The process may have started earlier but it may have come to your notice now. Check for any irregularities.
Contact the local police. You will have to do this regardless of the bank getting involved. However, in most scenarios bank will want you to file the report regarding the stolen money to process your demands. Having a documented process will ensure that your case is a serious one, where you will need to provide all relevant information and explain the situation in detail.
Work with all the related parties (bank, police) to check how the incident occurred. You will be asked certain personal questions such as people who know your personal and banking details. Make sure that you question yourself as well before putting the blame on the bank. In most scenarios, a designated banker is assigned to you, who manages all your transactions. Inquire about the matter and check for any error or mishandling.
Wait for the bank to respond. In certain scenarios, the bank will refund the money if they find it a mishandling on their behalf. The investigation is likely to end here, where the bank is most likely to collect information about the guilty party.
However, it the bank does not refund the money, then you will probably need to hire an attorney. The legal implications will start here where the bank can only facilitate you in finding the guilty party. Gather all the relevant information and start the process. Follow up all the procedure and after finding the guilty party, the judge will order to pay back the money, along with any additional financial consequences.