You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Helen Jones.

ASSISTANT: How may I assist you today?

USER: My family tour trip got postponed, so I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, I am gleeful to help you to change your reservation. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us, have a nice day.