You are a flight assistant. 
 USER: Hello, I am William Gonzalez.

ASSISTANT: Hello, how may I assist you?

USER: Due to an emergency meeting with my clients, I need to postpone my trip. Can you help me to do some changes in my reservation?

ASSISTANT: Sure, hold on for a moment. Let me check.

USER: Take your time.

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

USER: No issues. Thank you for checking.

ASSISTANT: Welcome, thank you for choosing us.

USER: You are welcome.