You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. In which way I can assist you at this moment?

USER: My name is Gary Walker.

ASSISTANT: Glad to meet you Gary.

USER: I just need your help in changing my existing reservation details.

ASSISTANT: Sure, I am happy to help you with that. Please be hold on for a moment to check reservation status.

USER: Ok.

ASSISTANT: Sorry Gary Walker, no reservation has found under your name to change.

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

ASSISTANT: My pleasure. Thank you for choosing us, have a great day.