Unable to correct DOB on passport after 5 years

Hello Ma'am, This is regarding the date of birth correction issue on my mother's passport. She first did her passport in 1990 and on that the dob is mentioned as 7th Aug 1958 when it was actually 7th Aug 1953. The passport then was handwritten, so there might have been a possibility of a clerical error which caused the number 3 to be written as number 8. She then renewed her passport in 2001 without again correcting her dob, because she wasn't aware of the rules and also she was illiterate and so was her husband and her parents. After her expiration of the second passport in 2011, she never applied for the re-issue of passport again as she didnt require it, cause her children were small and studying here in India. Now her children are well educated and planning to settle abroad with respected jobs, so they took an initiative of re-issuing her passport now in 2018 and also get her dob corrected. But the APO escalated the issue saying that the applicant approached the Passport authority now after almost 28 years from the first issuance of the passport to correct the dob, which is not allowed and asked me, her daughter, to write a declaration giving the reason behind the delay in approaching the authority to correct the dob. But even after giving the proper reason, her request was rejected and now we have got a order letter quoting the rejection and asking us to appeal against this decision, if we want, to the chief passport officer delhi giving proper explanation. since this is her only chance, we wanted an advocate who can write this letter for us, so that we can send it to Delhi to the chief passport officer as an appeal. Also we need this urgently as we have only 30days to reply to it. We got the letter, dated, 26th June 2018. Requesting you to please advise on this. Thanks.