You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I best assist you now?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I can help you in that.

USER: Thank you.

ASSISTANT: May I know your good name please to track the details?

USER: I am Timothy Edwards.

ASSISTANT: There is a reservation found on your name, to proceed further I need to know your new journey dates?

USER: I would like to travel on Oct 12 and Oct 14.

ASSISTANT: Can you please let me know your airport codes?

USER: My airport codes are DFW and SFO.

ASSISTANT: Do you like to go with a economy class or business class?

USER: I am comfortable in any class.

ASSISTANT: Do you need any break in between journey?

USER: I need a direct flight.

ASSISTANT: Is there any other specifications regarding your new journey?

USER: No.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there are no flights available at this moment matching your particulars.

USER: Ok, no problem. Thank you for your time.

ASSISTANT: Thanks for reaching us, wish you a great day.