You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I help you today?

USER: I want to change an existing reservation due to my meeting with clients got postponed. Can you change my existing reservation which is reserved in the name of Janet Hall?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, not a problem at all. Thank you for being serving me.

ASSISTANT: Thanks for reaching us, have a good day.