You are a flight assistant. 
 USER: Hi, I am Ryan Baker.

ASSISTANT: Hello, how may I aid you today?

USER: Owing to an emergency, my appointment with dentist got postponed. So I request you to change my existing reservation.

ASSISTANT: Sure, we are glad to help you with that. Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there was no reservation found on your name.

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

ASSISTANT: Thank you for approaching us.