You are a flight assistant. 
 USER: Hi. I am Betty Green.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Sure, just a moment please.

USER: Ok.

ASSISTANT: I am sorry no reservation found on your name.

USER: No issue, thank you for your time.

ASSISTANT: Thank you for using our service. Have a great day.