Need Expert Advice on Employer's Cheating

I had given an interview with a company who supplies mobile accessories to large retail chains in India. In an interview in company's board there was three directors, two was handling indian operations and one more director from abroad. initially I was not happy with the package offered by two Indian directors, but after discussion with another director (who was also Indian but stays in abroad and handling business from there) he offered me as per industry standard for which I agreed. I asked for offer letter but initially they refused and after continuous follow-up they sent me copy by mail then I joined. After joining I asked for appointment letter for that they said will issue in few days. They hire me for there new project and for which I have to travel at various locations. So I never get time to sit in office and ask for appointment letters. After successful one & half month, one day suddenly both Indian directors called me and told me that project for which I hired is delayed and told me to quite. I understand the situation and it was mutual understanding between us that I resigned (No paper works). So I informed this situation to that director who was in abroad and requested him to release salary for full month instead of 20 days of that month. I sent a mail to all directors requesting for full months salary. The director who was in abroad (who is final authority) approved my request and replied that we will pay you full months salary. But when they released the payments they released only for 20 days. I was very disappointed and asked for reason now both Indian directors are replying we will update you. Now I don't trust these people. I tried to contact the director who is in abroad but he is not answering. I am loosing good amount, for which I worked very hard. Now how should I handle this situation ? even after approval from final authority of the company. Please help me with what are the action I can take. I have all email communication & What's app chat records with all these directors.