You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I support you?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, we are here to help you. Please let me know your good name to proceed further.

USER: My name is Kathleen Williams.

ASSISTANT: There is a reservation found on your name in our data. Can I have your trip dates?

USER: I want to fly on Oct 18 and return on Oct 20.

ASSISTANT: May I know your respective airport codes?

USER: My airport codes are IAH, ORD.

ASSISTANT: Do you have any break in between journey?

USER: I need a single connection.

ASSISTANT: Is there any other specifications for you?

USER: I don't have any other specifications.

ASSISTANT: We are regret to inform you that, no flights are available on your journey dates.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for choosing us.