You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you now?

USER: I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, I can help you.

USER: Thank you.

ASSISTANT: Can I know your name for checking your flight ticket booking?

USER: I am Jack Robinson.

ASSISTANT: Thank you for being on hold, I have checked with your information in my portal to change your booking but is displayed that there is no user name found to change it.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for reaching us. Have a nice day.