[Resolved]  Indigo Airlines — not allowed to board my flight even after arriving in time

Address:

Allahabad, Uttar Pradesh, 211012

I had booked my 12:50 p.m indigo flight for Delhi for 14th, June, 2019. I had arrived 1 he before and was in line for the check-in. It was still displaying on the screen above the counter that the check-in is in progress. Soon after the check-in was aborted. They said we were late and had to come 2hrs before. The flight could not be boarded now.
I want to enquire that are there any such rules for not allowing a person to board if the counter line is not moving? Are we supposed to fight our way through?
The indigo check-in criteria for domestic flights clearly states that check-in counter closes 45 mins before. People arriving even 1hr 15 mins before were denied check-in. The snapshot has been attached for the same.
Moreover, indigo sends messages every now and then but failed to inform a customer that we are not allowed to board since we are late. We have to wait to come to the airport, then stand in line, then denied service.
They even failed to give us anything in writing for why exactly they had denied check-in. We have to take there word for it. Sheer unprofessional way of handling situations?
I also heard them speak about something called "Overbooking". What is Overbooking? The flight is allowing multiple customer to book flight even after the capacity is full. This is so that everything works out in their favor. The customers who arrive first get the seats, and the rest are said you came late.
The Allahabad airport is not that big that everyone has to arrive 2 hrs before.
Then, they provided me with a solution. They said I have to pay RS 1500 and can take the next indirect flight via Banglore or Pune. How convenient? And that check- in, out of the box could be done even 40 mins before. For the same airways? Rules change according to their convenience?
They should consider cases where people can get late for no fault of there own. Everyone is learning these things. They should be flexible in cases where students or at least females are travelling alone. When already the frequency of flights is less why are they behaving as though the airport is crowded.