You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, Good Morning.

USER: My name is Frank Williams.

ASSISTANT: How may I guide you?

USER: I have already booked my ticket to Houston but due an medical emergency, my trip got postponed.

ASSISTANT: Ok, do you want me to change your existing reservation?

USER: Yes.

ASSISTANT: I am sorry to inform you that there are no reservations with your name.

USER: No issues. Thank you for your information.

ASSISTANT: Thank you, have a good day.