You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please help me with the name on which the booking is done.

USER: My previous reservation has done with the name Christine Harris.

ASSISTANT: Thank you. Please allow me a minute.

USER: Sure.

ASSISTANT: Christine Harris, I highly regret to inform you that there is no booking found on your name.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you for understanding. Thank you for utilising our service. Have a great time.