Transfer Certificate

My brother completed his schooling from class VI to XII from Jawahar Navodaya Vidyalaya (JNV), Choppadandi, Karimnagar District, Telangana State. The JNVs are functioning under the Ministry of HRD. At the time of school leaving, the principal has given the remark 'satisfactory' against the line 'character' in his Transfer Certificate. She gave the same remarks to all students. The college in Kerala where my brother sought admission in B.Sc. (Psychology) refused him admission, demanding that at least 'Good' should be there. We requested the principal to issue a conduct certificate or a simple sentence mentioning his character as 'Good'. She refused in spite my request to do so. Even my written application to her was not accepted. My brother, though qualified for the seat on the basis of his marks in the CBSE exam, has lost an opportunity to study in a college of his choice in Kerala. I requested the Principal's immediate officer's in the organisation (Navodaya Vidyalaya Samiti, Hyderabad) but she refused to listen to them. What should I do now?