You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Jonathan Miller.

ASSISTANT: How may I help you out?

USER: I would like to change my existing reservation, due to postpone of my scheduled examination dates. Can you please help me in changing?

ASSISTANT: Sure, I will help you in changing the ticket.

USER: Thank you.

ASSISTANT: Sorry, there are no reservations found.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.