You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am Sandra Jackson.

ASSISTANT: How can I aid you?

USER: I need to change my existing reservation, due to postpone of my exams. Can you please help me with that?

ASSISTANT: Sure. Give me a minute.

USER: Sure.

ASSISTANT: Thanks for your time.

USER: Ok.

ASSISTANT: We didn't found any reservation by this name.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you.