You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you now?

USER: Could you please change my existing reservation due to postpone of my trip?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your good name?

USER: My name is Ryan Robinson.

ASSISTANT: Thank you for your name, sorry there is no reservation found on your name in our system data to change it.

USER: Not a problem, thank you for checking.

ASSISTANT: Thank you for visiting us, we hope see you again.