You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am planning to change my departure and arrival day in my existing reservation, can you please help me out?

ASSISTANT: May I know your name please?

USER: Sure, my name is Joseph Adams.

ASSISTANT: Please wait a while. Sorry to say, there is no reservation on your name in our database.

USER: Ok, take your time. It's ok, thank you for the information.

ASSISTANT: Thank you for opting us.