I am really shocked to listen your situation. Yeh FPSC ka aik bohat bara drawback hae ke yeh late application accept nahin krti. 2ndly when we apply, it is written on aplication conditions that our candidature remains probitionary till whole of selection process.First i shall share my experience with you and then i shall give you some recommendations.
I also faced same situation 5 years ago. I qualified written test for a FPSC post and some days later i received a letter that my application was received after office hours on same day. I made an appeal and 2 of FPSC members heard me and insisted that my application was late. Magar jiss cheez ka muje sab se ziada dukh laga, wo yeh thi ke muje unhon ne usi din hearing he liye bulaya aur usi din baqi candidates ko interview ke liye bulaya. It means FPSC members were mentally prepared not to give my appeal any weightage. I got much disgurted but you will be dishurted more than me because I guess you cleared written part and that s why they are verifying basic requirements of applicants before announcing result.........So your written part is pass....Congrats....

For yoyr hard luck, you insist not on FPSC but also go to judiciary otherwise FPSC wil ruin your.....They did it according to law. But you can take plea that if my application was late, why they accepted?

Good luck,,other members too coment, for our shallow water friend s situation.