You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may 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, please share your name?

USER: Mark Davis.

ASSISTANT: No reservation found on your name.

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

ASSISTANT: Thank you.