Interpersonal Breaks

In the past three months Ruth Disselkoen, has cut her breaks short to complete her work, complains of being tired, and twice a month requires overtime hours, which causes the company an additional $200.00 a month; on the other hand, Frank Daley, has complained about the her poor work quality. Whereas, Jack Snyder seems to have little work to do, he arrive late twice a week, he takes extra breaks; although his work is always professionally completed. Even though, nothing has changed in their personal lives. I would like to have interpersonal meeting with both Jack Snyder, and Ruth Disselkoen to investigate the root of the problem, so I can determine my next course of action, and if I have the authority to implement any of the changes necessary