You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: Owing to an emergency, I want to change an existing reservation, can you please help me in changing the reservation?

ASSISTANT: Sure, I am gleeful to help you and can I know on whose name the flight ticket has booked previously?

USER: Please check with the name of Anna Walker.

ASSISTANT: Thank you for your information, please wait for some time to check your previous booking.

USER: Sure.

ASSISTANT: Thank you for your patience, I regret to inform you that I am unable to modify your flight ticket because there is no ticket found under your name.

USER: Not an issue. Thank you for your information.

ASSISTANT: You are welcome and have a nice day, thank you for reaching us.