Diploma

Programs in forensic auditing, also called forensic accounting, train students to examine the books and financial histories of businesses for acts of fraud or misconduct. Certificate programs and Bachelor's and master's degrees are available in the field.
Forensic accountants and auditors investigate corporate misconduct and financial scandal, combining the skills of accountants and investigators. Many schools offer forensic accounting courses or minors within an accounting field of study, though a few include undergraduate majors and graduate-level programs specifically in forensic accounting.
There are two type of courses available :
1) Certificate Course in Forensic Accounting and Fraud Detection
2) Post Graduate Diploma in Forensic Accounting
Several institutions are offering training and education to become a good forensic accountant. Indiaforensic, Pune is one of the few, which conducts a certificate course in forensic accounting and fraud detection. The Institute of Chartered Financial Analysts of India University, Tripura also offers a postgraduate diploma program in forensic accounting.

My personal suggestion would be NONE. If you think that you are a cabin crew material, please apply for all the available vacancies with the airlines. If you get selected, they train you in any case. Airlines do not trust on the training acquired from institutions. The only help you get from the institution is that of the interview dates.
In the interview, no airline will ask you any questions about Safety, First Aid or Services coz they are airline specific when it comes to service. But yes, if you are an experienced crew, be ready to answer a few technical ones. In your case they judge you on your personality, grooming, communication and BMI.
To talk about the training, Jet Airways provides one of the best training and that lasts for about 3 months.
Therefore, scrap the idea of joining a private institution to be trained on cabin crew attributes and don't waste your money.