Did they get too fast or too slow? If they were acting unprofessional and caused the airplane to get dangerously close to a stall or mach tuck then action needs to be taken. The problem is that it's your word against both of theirs. Not much you can do unless you can prove that this actually happened. My advice: Don't EVER ride on any MESA operated aircraft. Don't put your loved ones on those airplanes either. If you do you're taking a gamble. You could have a competant crew or chances are a crew who does not give a rip about operating safely. That's why they are at Mesa. They most likely were turned down at numerous other carriers for being clueless tools.
Welcome to the world of the bottom feeders. You get what you pay for. Sub par pilots operating at a sub par airline.
Could you please post a message with your name and airline that you work for and we will help make sure you don't get a ride on any airline that might endanger your life. Please tell me that you are not a professional pilot.