Air India — Not allow to boarding in flight

Address:

New Delhi, Delhi, 201304

I have a flight from delhi to blore AI 174 on 30th nov. I got the message from customer care that flight was delayed 15 mins. I already done web check in and reached at for bagage drop at 5:10 before 35 mins just to drop bagage. But there was attendent Mr. Gandhi did not allow me to board the flight and said boarding gate closed. And forced me to book another flight. I requested number of time but he did not allowed and talked bery rudely. I got the call from gate at 6:30 and flight was take off at 6:40. Why they did not allow me to board the same flight? Was that the intentionally did to me? Why that guy does not know how to talk to girl? Why they insulted me and forced me to go in another flight? Pl