Dear Mr Ram,
In an NEFT or RTGS transfer request, if the details of receipient are not matching with the details provided by you viz, name of account holder, account number, bank and branch details (inc Bank Branch code), the transaction is bound to fail and money returns to your account.
Now in your case either you provided all the details in such a manner that they matched with the wrong recipient (which is highly impossible) or the bank has credited the wrong account even after noticing the discrepency.
In first case it would be very difficult for you to prove that the transaction was not intentional as the duty was casted upon you to provide correct details of rcepient and assumption is that you have indeed provided correct details. In such case the bank cannot help you at all and as learned lawyer friends suggest, only a legal action (I wonder under which provision of law) can help you.
If you are fortunate enough to fall under second case, then the mistake lies with Bank and you can persue the bank to revert the transaction as the same has been inadvertantly credited in wrong account. You have to get a copy of NEFT/ RTGS instruction in records of bank and take up the matter with higher level failing which to Ombudsman. It is akin to crediting a cheque issued in name of X in account of Y only because in the deposit slip account number of Y was mentioned. This is simply not permissible.