Appointment Confusion

How can you confuse an appointment?

A social worker called to see about an appointment for a patient. The social worker stated that she wanted to reschedule an appointment. Upon checking the system, the patient missed their appointment. So I will schedule an appointment. This is how the conversation went:
SW: I would like to reschedule an appointment for this patient. The patient missed her appointment.
ME: If the patient missed her appointment, then we need to schedule an appointment.
SW: No, no. the patient had an appointment but missed it. So I would like to reschedule that appointment.
ME: If the patient never made the appointment, then I can schedule an appointment.
SW: I called and someone gave me an appointment for the patient on 8/4/2017.
ME: There is no appointment for that date in our system.
SW: I called an the guy gave me that date for the patient.
ME: Maybe that appointment was scheduled somewhere else, because I do not see 8/04/2017 in the system. Patient has a medical appointment on 9/___ with medical.
SW: Yes, I made that appointment.
ME: All right. The next appointment is November___.
SW: Thank you. Who is the patients' therapist?
ME: The patient does not currently have a therapist. The patient was discharged and has to start over.
SW: When was the patient discharged?
ME: 8/___.
SW: All right, Thank you.
ME: You're welcome. Have a great day.