Yes, it is possible to reschedule an interview at IIM Bangalore, IIM Calcutta or any other IIM. If you can’t attend the interview, for some reason, you can write a mail and request them to give you another interview slot. You should explain the reason and attach proof with the mail. For example, if your semester examination dates are clashing with the interview date, you should attach the examination schedule with the mail.
For valid reasons, they agree to reschedule.
Usually, it is seen that the staff at IIM Bangalore and IIM Calcutta are quite cooperative and flexible according to the students.
Thus, we can say that by following the above procedure as discussed you can get your interview round rescheduled at IIM Bangalore and IIM Calcutta.