You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Meeting a family friend got postponed, will you help me to change my existing reservation?

ASSISTANT: Sure, can I know your name?

USER: Sure, my name is Sandra Clark.

ASSISTANT: Ok, please hold on.

USER: Sure.

ASSISTANT: Sorry, no reservation found on given name.

USER: Ok, thank you for your information.

ASSISTANT: Thank you for reaching us.