You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: My name is Alexander Clark. I have already booked a ticket to Boston but due to an emergency, my trip got postponed.

ASSISTANT: Would you like me to change your reservation?

USER: Yes.

ASSISTANT: There is no reservation found on your name.

USER: That's fine.

ASSISTANT: Thanks for choosing us.

USER: Thank you for your time.