I ran into that same problem where you could only go back as far as your grandparents. I then enlisted my mother's help in requesting records. But, there is a silver lining. The Registro Demografico records going back to 1885 have been filmed for Ponce and many other municipios by the LDS (Mormon) church. A fee of $3.75, which covers mailing, will send a film with quite a few years worth of information to your local Family History Center for a period of 1 month. Films can be extended. If you live in the NYC area, many of the Ponce films are on permanent loan at the Plainview, Long Island, Rego Park and NYC Family History Centers due to researchers who paid additional monies to have them on permanent loan and be able to go back and review them again.
The convenience to using this option is that there is not any restriction other than you cannot remove the microfilm from the Family History Center. You can make copies of the entries and this will provide you with more information than will be given to you on an extract certificate from the Registro Demografico. Best of luck!