Doubt

Hi guys,
Can anyone guide me through this..... 
I had filed my Dad's individual tax return last year through online... Now one mail came that there is a mismatch in the details which i had provided... the mismatch is the date of the amount paid in bank... it should have been 14/6/12... by mistake i had given 14/4/12 in the return... now what am i supposed to do...
It would be so kind of u if u can guide me through this...