Dob change in ssc certificate

My son DOB changed in SSC ( 1993 instead of 1992 ) and 7 years passed ?

I approached Board and they replied that it is not possible to change after one year. 

I want to change it as per DOB issued by govt.office at the time of birth.

Is it possible to change it ?

If so, Who can help me in this regard / Whom I have to contact .