You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I provide assistance to you?

USER: My name is Patricia King. I want to change my existing reservation due to postpone of client meeting.

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Sure.

ASSISTANT: Thank you for waiting, we are sorry to say that no reservation was found in our database on your name.

USER: No issue, thank you for your service.

ASSISTANT: Thanks for your approach.