You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am Benjamin Thompson.

ASSISTANT: How may I be of your help?

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

ASSISTANT: Sure, I'll help you with this.

USER: Thank you.

ASSISTANT: Please wait a moment I will check the reservation status.

USER: Sure.

ASSISTANT: Thank you for waiting, unfortunately there is no reservation found by your name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for choosing us.