You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I would like to change my existing reservation, which is done recently. Can you please help me out?

ASSISTANT: Sure, I'll try to help you in changing an existing reservation.

USER: Thank you for considering my request.

ASSISTANT: Please let me know your name to check the reservation list.

USER: Myself Frank Robinson.

ASSISTANT: Thank you for providing your name, give me some time.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for waiting, sorry to inform you that there is no reservation found by this name.

USER: Not an issue, anyway thank you for the information.

ASSISTANT: Thank you for approaching us.