Ours are managed by the H&S committee which is made up of management, supervisors, crew and admin staff. We have them on a roster to be discussed, and then if there is any relevant changes that need to be made, it is done that day.
Surely if the company requested him to do the extra hours, they would have known he was doing a 7 day week. Knowing that, he could have come in later on the Monday ensuring he had an 8hr rest break between shifts or he been paid for a rostered day off. But i would certainly not believe he should be taking annual leave when they have asked him to work the extra time.