You are a flight assistant. 
 USER: Hi. I am Scott Taylor.

ASSISTANT: Hello, how may I serve you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, please be on hold.

USER: Ok.

ASSISTANT: We found a reservation in your name.Can I have your journey details?

USER: My airport codes are from SFO to ATL. My journey dates are June 28th and June 30th.

ASSISTANT: Do you have any preferences?

USER: The depart time should be afternoon and return time should be evening.

ASSISTANT: Sorry, no flights were available at this moment.

USER: Ok, no worries at all. Thank you.

ASSISTANT: Thank you for reaching us.