What should i do when I get an unfair treat at my work?

I applied for a position, Admin Assistant: Procurement , which was new open at an NGO. I had worked for 1 year, my supervisor, Admin officer resigned. I had assigned to take in his place without compensation for 13 months. Then a new person came. I didn't apply for his position because they said male should be fulfilled into this position. Within two years, this NGO have developed and had 4 more centers support. Then my work has became overload. Even there are a lot of challenges, I have acknowledged that I get my work done well and successful all the time. During these four years, I have advocated for my compensation via verbal and email to management lines, but there was no respond. Currently, new structure comes, I become Procurement Assistant and there is another place to recruit to be my direct supervisor, Procurement Officer. I am not promoted, but I applied for this position, which I have been working a lone. During the recruitment process there were no one selected include me. They decided to re-announce. I had no right to apply again. I found that there are two candidates, who are selected to be interviewed for this time. I have known them before. They do not have background and experiences with procurement. Now I am waiting to see the result. Will they select one of them? If so, I don't know how to face to this issue, while I feel so unfair. A non-qualify person comes to be my supervisor. Should you give me some ideas? Recently I have been so stressful with my current job. I want to change my job, but I don't have a chance yet. It is not easy to find another job here. What should I do? I feel it is so unfair to me. Please kindly share your ideas. Thanks in advance for your kindness.