You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: I am Joseph Clark. Could you please help me to change an existing reservation as my trip got postpone?

ASSISTANT: Yes, I will help you with your concern.

USER: Thank you.

ASSISTANT: Can you please wait a moment while I check?

USER: Sure.

ASSISTANT: Sorry, there are no flight tickets found on your name to change.

USER: Ok, not an issue.

ASSISTANT: Thank you for choosing our agency.

USER: Thank you for your information.