How to quash dismissal order

Respected Sir/Mam Greetings ! I am a student of class XII from Meerut, UP. The following case is of my father, who was in BSF.and was dismissed from BSF in year 1997. The commandant issued notice: 1. Saying his performance is poor. 2. He got three punishments during his job of approx. 7 years. (i) Overstay of leave - 14 days RI - Due to appendix operation (ii) Disobeying a lawful command of officer - 7 days RI (iii) Overstay of leave. - 7 days RI - Due to jaundice He presented his medical documents in case (i) & (iii). He also own them today. While commandant rejected medical certificates & dismissed him using his power of Rule 26 of BSF Acts & Rules. My father doing struggle from last 19-20 years. Now he want to file a petition in court & want to quash his dismissal order with all back wages & consequential benefits. Please help.