You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Could you please change my existing reservation due to postpone of my exams?

ASSISTANT: Sure, may I know your name?

USER: My name is Donna Allen.

ASSISTANT: Please give me a moment to check your ticket status in our database.

USER: Sure, take your time.

ASSISTANT: Sorry Donna Allen, no reservation is available by your name.

USER: Not a problem, thanks for checking.

ASSISTANT: Thank you for choosing us.