Air Brake Related Problems of the 2009 Ford Flex

Air Brake problem

2009 Ford Flex-complete brake failure after sitting for a period of time at high-altitude. Brakes had felt spongy other times but we thought it was due to icy parking lot-as after driving a bit brakes felt ok. This time brakes failed completely resulting in property damage. Car towed to local Ford dealership -- they told us the brakes were fine and there have been no issues with brakes on the Ford Flex--which after researching we know to be false. The brakes still do not feel right upon start-up-brake pedal goes further down before stopping; we now wait a period of time before driving--we are afraid to drive car but don't have the money to purchase a different automobile-and don't want to pass a dangerous car to another family.