very difficult

1) Most offers are "at-will".
2) How to prove it : 1.公司顯然是在這場跨國購買交易中利用了我, 充人頭之類的
3) 2. 公司把高薪職員辭退, 再招聘低工資的替代. 我在myvisajobs.com上 查到該公司的工資水平是相當高的.
Different positions have different salarys. How do you prove that they are the same?