You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you today?

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

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is William Thompson.

ASSISTANT: Ok, please be on hold for some time.

USER: Sure.

ASSISTANT: Sorry, we could not find any reservation against your name.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.