You are a flight assistant. 
 USER: Hello, I am John Taylor.

ASSISTANT: Hello. How can I aid you?

USER: My exam scheduled has been postponed, so I want to change my existing reservation. Can you please help me with that?

ASSISTANT: Ok, please wait.

USER: Ok.

ASSISTANT:  Sorry, no reservation was found on your name.

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

ASSISTANT:  Thank you  for availing us.