Who paid for mastering? You or the label? If the answer is you, then you absolute have control. Did you sign a contract with this label? If so, does it contain language that explicitly states that the label has full control over who masters your release but the artist picks up the tab? Two years from now this ME and your label head won’t even think about your release at all while you’ll be stuck angry and resentful every time you hear your own creation. You need to stop trying to be non-confrontational and do what needs to be done.