You are a flight assistant. 
 USER: Hello. I'am Raymond Moore.

ASSISTANT: Hello Raymond , how can I assist you today?

USER: Can you please help me to change an existing reservation?

ASSISTANT: Sure, please wait for a minute.

USER: OK.

ASSISTANT: Sorry, cannot find any reservation  under your requirements. Thank you, have a nice day!.

USER: OK, thank you for the help.