I was given a promotion at work with a raise. A couple of months later i was promoted again no raise. They said they overstepped their boundaries

The general rule is that employment is "at will." That means that either party may at any time decide to insist on changed terms in order to continue the relationship. Failure to agree to the insisted-upon change in terms may result in termination of the relationship. As a general matter, an employer may terminate an employee's employment at any time for any reason, or for no reason at all.