You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Donna Lewis. Suddenly I got a call from my manager to attend a meeting on same departure date, so I need to change my existing reservation. Can you please help me?

ASSISTANT: Ok, please wait a moment.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, there is no flight ticket been reserved on your name.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for choosing our agency.