Indian Railways — change of platform without notice

My parents had to travel from delhi to una himachal on 01 nov 17 by train no 14553 in 2ac at birth no a1 17 and 18. They were waiting from 2130 hrs at old delhi railway station at platform no 14 as the display board was showing that train no 14553 will come on platform no 14. But at last train came at platform no 15 and it left the station. And along with my parents so many other passengers missed thier train. My complaint is that who is responsible for this and what about the fare and inconvenience.