Birth Certificate Error (Manila)

Hi everyone - My wife, a Filipino, has an error on her birth certificate. Originally, we obtained an notarized affidavit from her mother explaining this error. Affidavit was used for Marriage contract, Filipino passport, US green card, Naturalization certificate, and a US passport. Trying to get dual citizenship and we find Filipino Government no longer recognizes affidavit. Not sure now how to get problem fixed since we're still in the US and would prefer not having to fly to Manila. Mother is still alive but 90 yrs old. Has anyone experienced this and if so, did you get it corrected and if so, how? Philippine Embassy in LA is of no help. Thanks.