You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am Brenda King. I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no reservation matches with given name.

USER: No issue, thank you for your service.

ASSISTANT: Thank you for approaching us.