had to pay extra unnecessarily for rescheduling a flight on flipkart flights, for a mistake which was from their end. kindly advice.

i booked a flight from flipkart fight today from mumbai, i booked a flight of 6:25am on 5th jan, after making the payment, I received a message from indigo airlines that the flight has been booked of 10:15pm of the very same date. i did not even check that flight since I have to travel for my exams which is at 2pm on 5th. i immediately called the flipkart flights customer care and explained them the scenario, no matter what I told them they still insisted me to reschedule the flight because it's my mistake(even though it isn't) I asked them why would someone call you immediately after booking a flight and ask you to reschedule it just to pay you 2.8k extra, they told me that if you want to complain you can send us a screenshot on email, I asked them if they ever took a screenshot or recorded their screen while booking tickets? i have rescheduled my flight and want to lodge a complaint against flipkart since I have been unnecessarily scammed for extra money kindly suggest me ways to do it, thanks