You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I assist you for the day?

USER: I am Melissa Johnson. I want to change my existing reservation due to some issues, can you please help me with that?

ASSISTANT: Sure, I am here to help you. Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, we found no reservation on your given name.

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

ASSISTANT: Thank you for reaching us.