Unless the involvement in serious crime is established it is not possible to freeze the account. You have not informed whether it is a private sector or Public Sector Bank. Generally, they have to use Garnishee order type freezing.
Any way, first seek information from Bank as an affected party the reasons for such freezing, the stipulation in their laid down rules for such seizure, the correspondence from such law enforcement authority confirming the same through hard copy.
Then file application and seek specific information under RTI to that law enforcement authority the specific reasons for freezing Bank account, and copy of their circular/directive/notification/norms that empowers them to freeze the account without any preliminary investigation and powers of those authorities.
Armed with all documentary evidence, contact an Advocate for proper legal guidance.