You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Ok, please stand by I will revert you.

USER: Ok.

ASSISTANT: Thank you, sorry no reservation found with your name.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us, have a nice day.