You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: As my exam got postponed, I want to change my existing reservation. Can you help me out?

ASSISTANT: Ok, sure I will help you with that. Mean while may I know your name?

USER: Sure, my name is Jerry Green.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: That's ok, thank you.

ASSISTANT: Ok, thank you for reaching us.