You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I assist you?

USER: I am Helen White. My Business meeting has been postponed so, I want to change my existing reservation. Can you please help me with that?

ASSISTANT: Sure, please give me a minute.

USER: Ok.

ASSISTANT: Sorry Helen, there is no reservation available on your name.

USER: Ok, no issues. Thanks for your service.

ASSISTANT: You are welcome.