You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My name is Alexander White. Can you please help me in changing my existing reservation details?

ASSISTANT: Please wait a while, I will check and inform you.

USER: Ok.

ASSISTANT: There is no reservation on your desired travel dates.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for opting us.