You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I am Mark Edwards. I have an appointment with my client in Houston, due to some officials problems my appointment has postponed. Can you please change my existing reservation?

ASSISTANT: Ok, I will help you. Please wait a moment.

USER: Sure.

ASSISTANT: Thanks for your patience. There was no reservation found on your name.

USER: Thank you for your information and service.

ASSISTANT: Thank you for choosing us.