Air India - Not allowed to board even after web checkin

My wife travelling from Chennai to Kolkata on *th August was not allowed to board by Chennai Air India officials citing she had arrived late (arrived at **:** A, M for a **:** indicated time of departure) She was travelling from Chennai for the first time and didnt know tamil -when i suggested they hear me on phone - the officials refused to take the phone . After **-** mins of this discussion when we finally said we can leave our checkin bag and just travel with the hand baggage and airline refused again saying there was now way they can help us to hand over the baggage she had left with me who was outside the airport.
All this time, the airline staff kept saying we can assist you to make booking for Indigo flight departing next after *.* Hrs, instead of facilitating the passenger to board the Air India flight -looking very suspicious.
I had to then book the Indigo flight left with no option as my wife was to reach Kolkata the same day.
The staff at counter No ** behaved very rudely and rigidly. The Airline counter staff were also unhelpful. The manager Mr. Srinivasan claimed he could have helped in case this was brought to his notice earlier
from **:** to ** my wife kept trying to board but was denied entry by the Airline counter staff
This led me to a lot of financial losses (extra ticket booking costs, workday loss for me) as well as mental harassment. This was never expected from a reputed brand like Air India
We want this to be compensated by the airline as well as an issuance of an apology