You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I would like to change my existing reservation, please help me out.

ASSISTANT: Ok, please tell me your planned dates for this journey? Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Can I know your good name please?

USER: My name is Ryan Scott.

ASSISTANT: Sorry, no reservation was found by your name.

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

ASSISTANT: Thank you for choosing us.