You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Raymond Allen.

ASSISTANT: How may I assist you?

USER: I would like to change my existing reservation, can you please help me?

ASSISTANT: Sure, I am here to help with change reservation.

USER: Thank you.

ASSISTANT: Please wait for a minute, I will check the records.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry to inform that, there is no reservation found on your given name.

USER: That's ok, no problem. Thank you for checking.

ASSISTANT: Thanks for reaching us, have a nice day.