HappyEasyGo — extra quotation for change of flight on the same date.

I have booked two tickets from hyderabad to delhi for 01.02.18 by air india flight no ai 559, departure from hyderabad at 06.40 a. M. I wanted to change it to air india flight no. Ai 543 departure from hyderabad at 10.00 a. M. On same date. I have sent an email requesting for the same. I am asked to pay rs. 10, 154.00 for two passenger. The break up of the same is:- date change/flight change penalty :3500/- per pax
Fare differences : 1077/- per pax
Service fee : 500/- per pax
Total penalty per adult :5077/- inr per pax.
When i contacted executive of happyeasygo for any reduction, he has informed me that the same is the amount payable to air india, they have received the same from air india. Afterwards i contacted air india office, they have charged me rs. 5, 250.00 for two persons and have changed it. This is highly not at all appreciable.