Indigo Airlines — Preponement of flight

We had booked flight from Visakhapatnam to Hyderabad on September 5th, 2021 at 18:15P.M but yesterday we received a message that our flight got preponed and Departure by 17:35 P.M on same day. without our concern they just preponed for the sake of their business. we just asked them to reschedule to another fight after 18:00 P.M Hours as we have some important schedule on that day and not possible to catch the 17:35 hours flight. So we requested them to reschedule to another one after 18:00 hours or refund the full fare but they are simply answering it is not possible to reschedule and refund as well.