Unfair means at the boards examinations 2018 what to do

I received a memo regarding unfair means practice done by my son in 2018 10th std mathematics examination from the CBSE. As per the directive the candidate had to appear for a board meeting in Chennai. The college office told we have sent a report as its category 1 offence which is subjected to a penalty. When appeared before the committee there also we were assured it's category 1, hence we will just deduct the marks & impose penalty. And also told the memo of the penalty will be sent to the school. After 15 days they have sent another memo which states " Candidate is hereby informed to have used unfair means at the AISSE exam in the subject of maths and current examination is cancelled. He is eligible to appear in FULL SUBJECTS IN MARCH 2019. My question: Is there any legal means where the candidate can take just the MATHEMATICS exam and not ALL SUBJECTS There is Re Exam in the month of July. Is there a way where the candidate get a chance to appear for that?