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

ASSISTANT: Hello, how may I aid you?

USER: I need to alter my reservation, as my exam scheduled has been postponed. Please help me in changing?

ASSISTANT: Sure, I am here to help you. Please wait for a few minutes.

USER: Ok.

ASSISTANT: Thank you for your patience, we did not find any reservation on your name to change it.

USER: Ok, no issues. thank you.