Dear,
This is to inform you that while your work has been exemplary, but your absentee record is extremely poor. As you are well aware that work attendence is crucial to your job a and we also realize that your health has been poor, yet we have difficulty scheduling when we cannot depend on your Attendance.
We have discussed this subject with you several times in the past, therefore, once again we remind you that either your attendance must meet our requirements or we will have to terminate you.
Sincerely,