Central Board Of Secondary Education [CBSE] — Unfair result of my ward of class 12, please correct

Respected director sir,

My son HARSHIT roll no:26620059 studying in brahmashakti public school, begumpur, delhi school code:85175.

He scored 88.75(top 3 theory only) in class 10th, 90.2 in class 11th and as per his past performance we easily expect 88-95 in class 12 pre boards as the exact marks wasn't shared by the school.
Acc. To your criteria he should be scoring 88.7-92% in 12th but he got 74.2%
We asked the school authorities so they answered that this was the result of the moderation done by cbse and they haven't changed any marks by their end, what kind of moderation is this, ±5% might have been acceptable as per your policy, but a margin of 14/16% moderation is not at all acceptable by any parent.
He is preparing for IIT and next year onward when the relief in eligibility criteria(75%) would be withdrawn, he won't be eligible for the exam even though he is capable, you have destroyed careers and hopes of my ward, kindly look into the matter and correct the marks acc. To your 30/30/40 criteria.