You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I want to reschedule my trip as my appointment with doctor got postponed. So can you help me in changing my existing reservation?

ASSISTANT: Sure, we are here to help you out. Please wait a while. May I know your name?

USER: I am William Turner.

ASSISTANT: Thanks for being waiting. There is no reservation found by this name.

USER: Ok, thanks for the information.

ASSISTANT: Thank you.