You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Benjamin Martin.

ASSISTANT: How can I serve you?

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

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait for your response.

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

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

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