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

ASSISTANT: Hello, how can I serve you now?

USER: As my schedule of attending an conference got postponed due to heavy rains. Can you help me changing my existing reservation?

ASSISTANT: Sure, I will help you with that. Please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for the waiting, sorry to inform you there is no any reservation found on your name.

USER: Ok, Thank you for your information.

ASSISTANT: Thank you have a nice day.