icse school Not giving admission in school after class 10th

My name is Gargi Katyal.I have been studying in St. Mary’s Convent, Allahabad till class 10th. Now it happened that due to her sickness ( Jaundice) her attendance went below 75% which she even covered by going to school during her board preparation days.Now even after covering the attendance to 75% she was still called to school, denied her admit card , told to apologise or she would not be allowed to sit in her board exams. She even went to attend the school two days before the board examination even after completing 75% attendance. The medical report which she submitted to her class teacher Mrs. Namita Verma did not reach the principal and God knows what happened to that medical.I am sure it was hidden by the class teacher. Now after a lot of apologies she was given her admit card and allowed to sit in her board exams.Now after the board exams she was asked to come to school and get admission after results while all the other girls were allowed to attend the school. So a!
fter the results she secured 76% and now she is denied admission into the school without any proper reason. My parents almost going to school everyday but they are disrespectfully denied. The school is taking advantage of our problem. The staff of the school specially the principal and the teacher Mrs. Namita Verma are very rude and disrespectful. All the other schools have closed admission for class 11th. Please help me suggest me what I should do next. Is attendance such a big matter that I have been denied admission into the school?