How to correct Mother's name on child's birth certificate in Maharashtra (Pune)

My son was born in April 2015 in Pune, Maharashtra. His mother's name (My name) on birth certificate is typed incorrectly. On all my documents have my name as one before marriage. My son's birth certificate has my name as the name after marriage(the name which is on none of my documents.) We ignored this as we thought we will change her name later and we need not change the birth certificate then. Now we need to apply for his passport.My passport also has my before marriage name with the husband's name correctly mentioned. We mentioned same name in my son's passport application but my son's birth certificate has her name as after marriage(Again which is on none of the documents) So my son's passport application is stuck and objection has been raised by Regional Passport Office. How to get the name corrected on birth certificate? We wish to update birth certificate of my daughter to reflect my name consistent with all my other documents (before marriage name). Also how long will this process normally take?