Retracting Payment even though was covered

DONT EVER GO WITH FEDHEALTH they are *********!!! I cancelled my membership with fedhealth as it was becoming too expensive. They agreed to cancel my subscription and all is in order. I recieved all my statements that I dont owe a cent and even that they still owe me money and now all of a sudden two months later the hospital phones my wife to tell her they retracted their payment of the birth as we were not covered! This is utter bull my memebership only ended a month after on which they agreed was fine!!! I am also going to refer this matter to the ombudsman! Ive spend almost 80k on fedhealth for the last few years in fees and now they have issues paying things because I cancelled!!!