Indigo Airlines — gates closed and around 8 people were forced out

Address: 560079

Website: www.goindigo.in

Looks like this is now a kind of strategy.
I had a flight from bangalore to delhi on the 11th october at 6:05 am. However, the security check was so crowded that by the time i could finish mine it was 5:40 am and i reached the gate by 5:43 am (Had to sprint).
However, i was not allowed at the gate.. They (Mr raghavendran the then indigo manager) said the gates were closed at 5:40 am.
Well, we were around 8 people who hadn't boarded the flight.
I was asked to meet another attendant at gate 8c. The info was nothing but to take a ticket for the next available flight with a whopping extra cost of rs 12, 800 (For 4 tickets). I had not other option than to buy.
However, i later when spoke to my co-passengers heard this happened with them too and had to pay up 5k as extra and on discussion many more had seen the same experience.
One passenger a lady was to travel to chandigarh and had no money with her.. She was left crying not knowing what to do.

What kind of strategy is this? I once had a freak incident with spicejet just 10 mins for flight's departure.. They picked me up in their jeep and dropped at the flight. Why is this not the case with indigo..

What should i do now? Go with a consumer complaint?

Who is responsible for this.. Airport authorities? For the huge rush at security check or indigo? For not helping us get to the flight.

Why are we consumers being targeted..