[Resolved]  Indigo Airlines — complaint against miscommunication and behaviour

Hi i recently booked a flight for my father from pune to Raipur via bolore. Already did we check in before a day, he reached the airport on time, did security check-in, got boarding pass and informed him to proceed to gate number 3, now before the time, 20 minutes are remaining for flight to take, they informed my father that flight is already take off, door is closed .. he can't get into flight n no way he will be onboarding the flight, not was he only rude but also HE DIDN'T MADE ANY LAst time announcement also didn't call him, he requested him so many times like still time is remaining but he didn't listen at all . Later he sent a guy to my father saying we will put you on another flight FOR RS 6500 . Is this whats expected from such a big airline . If the flight was taken off prior time the airlines should take the responsibility instead of charging the customer by such illegal ways. If needed I can attach all the proof.. request to have a look in this case and help me out.