Check transactions from (statement starting date) to 8th feb.
Ex: Assuming you cleared everything in dec statement and you received statement in Jan 10th with due date as Jan 30th contains transactions between Dec 10th to Jan 9th in that statement.
Interest rate, assuming as 40.80% per annum.
Each day from Dec 10th to Feb 8th.
= (end day balance * 40.80%)/365
Sum of all should be equal to = 21600Rs. otherwise something went wrong, contact support.