Brake Master Cylinder problems of the 2010 Mazda MAZDA6

For many years and I've run into a serious issue with my current 2010 Mazda 6. Over the last five years I've had to replace the master cylinder multiple times, which I'm to understand from the mechanics is "extremely unlucky", however I feel there is another underlying issues. Attached is the brief timeline of the incidents based on the paperwork. Regardless of whether the car is in motion or powered down the car has ¿mushy brakes¿ with the brake pedal "collapsing" to the floor with little applied pressure. As you can see I have had three previous attempts to have the problem addressed, which were unsuccessful. The root cause of the issue was not even considered until a mechanic friend of mine suggested they look at the master cylinder as the root cause, which was looked at on inspection #3 through checking of codes and not finally addressed until inspection #4. I believe that there is a fundamental parts problem that is not being addressed by Mazda, which could have the potential for serious liability concerns for the company should there be any further defective parts manufactured and installed. I am comfortable saying that as I have not heard one comment or statement from gallo Mazda about contacting the manufacturer or Mazda corporate about addressing this issue. As of this date, the car is still having the "mushy brake" feel, with the brake pedal "collapsing" to the floor with little pressure and I believe the recently replaced master cylinder has begun to fail. The car will be returned to the dealership for repair. I consider it unfair and unethical to pay for safety/manufacturing issues that Mazda should address, not me as the customer.