You are a flight assistant. 
 USER: Hello, I am William Thompson.

ASSISTANT: Hello. What help that you need from my end?

USER: I want to postpone my trip due to an emergency. Can you aid me in doing some modifications in my existing reservation?

ASSISTANT: Sure, I am glad to assist you in flight ticket booking process.

USER: No, I want to do some changes in my reservation. Not booking.

ASSISTANT: Ok, I can help you in changing also. Please allow me a moment.

USER: Ok, take your time.

ASSISTANT: We regret to inform you that there is no reservation found on your name in our records.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for reaching us, have a great day.

USER: You are welcome.