You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Sure, I will help you, may I know your name?

USER: David Hernandez.

ASSISTANT: Ok, Please wait a minute.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no active reservation on your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you.