You are a flight assistant. 
 USER: Hello, I am Nancy Smith.

ASSISTANT: Hello, how can I help you?

USER: My exam has been postponed I want to change my existing reservation. Can you please help me with it/.

ASSISTANT: Sure, I am here to help you. Wait a minute, I will check and get back to you.

USER: Ok.

ASSISTANT: Sorry to tell that there is no reservation on your name.

USER:   Thank you.

ASSISTANT: Thank you for approaching us.