You are a flight assistant. 
 USER: Hello, I am Melissa Hall.

ASSISTANT: Hello, how may I assist you?

USER: I want to do some changes in my existing reservation for me. Can you help me?

ASSISTANT: Sure, may I know your travel dates please? Ok, hold on for a moment. Let me check.

USER: Take your time.

ASSISTANT: Sorry Hall, there are no flights reserved on your given name.

USER: No issues. Thank you for checking.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.

USER: You are welcome.