Indigo Airlines — Management mistake

This is regarding flight tickets which I have booked from Hyderabad to Vizag(6E 611).
My flight was on 13th Feb at 4:55pm.below are the PNR no’s :
PNR: RY8H2G
PNR: CGDCGB
PNR: H4C5MY
We reached and done with our check in formalities at 3:20pm at that time receptionist informed us that boarding time is at 4:10pm at gate 30B and we were in that floor from 4:00pm. By the time we reached near the gate it was around 4:35pm.
But no one were present over there near boarding and even we didn’t receive any final announcement for the passengers and the flight has taken off before departure time.
Generally we will get the final announcement several times before the flight takes off. But we didn’t even get that announcement. when we checked with indigo employee over there he said that we made the final announcement. But we are sure that they didn’t make the announcement.so I called to the help no which was provided in the ticket[protected] and informed them the same and I asked them to refund the same as it was not our mistake. They said that as per records you have entered boarding at 4:44pm but we didn’t do that we reached at 4:35pm as no one were present over there we tried to contact any one from indigo by the time we contacted it was 4:44pm and they noted that time in the records And even asked them is not your responsibility to give an final announcement.
I proposed 3 options, as under:
1. To cancel the tickets and give me Full Refund.
2. To accommodate me in the late evening flight on same day from Hyderabad to Vizag.
3. Or Lastly, to postpone the entire journey for next day ( i.e. 14th February)
For 2nd option they said that was the last flight for the day and for 3rd option they said that you need to pay 3800/- per head for next day. So I asked to refund my ticket charges, they said that we will provide the TAX amount.’
When I called to help no and informed all the above stated issues and questioned them why the final announcement was not made they were not providing the answer to that question.Is this the service does indigo provides to the customers.
Now I want my money to be refunded as soon as possible.
Otherwise I will go to court and file a case against indigo airlines.