Air India — lost my connectivity flight due to delay of air india flight

I was having flight from Chennai[MAA] to Delhi[DEL] on 31st May 2019 by Flight 539 @ 17:00hrs and connecting flight to Tehran by Mahan Air on 1st June 2019 @ 02:40hrs. The AI 539 got too much delay and finally it took off @ 22:45hrs [Delayed by 05 hrs 45Mins] and i informed Air India Manager Mrs. GokulaLaskhmi @ Chennai Airport about my connectivity flight and she was promising me to catch the connectivity flight. The flight landed @ Delhi @ 01:45hrs on 1st June 2019 and None of the airport staff is helping me to catch the flight at the end i missed that flight. AI stuff just gave me a delay letter which is not useful to me And i had spend £408.84 to purchase the another ticket from Ukraine International Airline. I would like to know
- why none of the AI staff is not supporting me @ Delhi to catch the flight?
- How AI staff, how she is promising me to catch the Mahan Air? even i told, if its not possible to catch the flight @ Delhi, please take back my luggage @ chennai Airport itself. i could find other way or stay in Chennai itself.?
- I lost one whole day salary + travel pain + return ticket @ Mahan air + extra payment o[censored]kraine Airline.

Kindly support to repay my concerns. Thanks