Hello student some of the best acting school are mentioned below for diploma
1)National institute of film and fine art, Kolkata.
2)Abhinav Acting Academy, Mumbai
3)Parks college, Trippur
4)Indira school of communication, pune
5)Asian Academy of film and television,Noida.

Duration of the course :-3years
Eligibility :-10+2 (pass or appearing) from any stream with any recognized board


Feel free to comment if you have any doubt
Good luck