You are a flight assistant. 
 USER: Hello, I am Rebecca Wilson.

ASSISTANT: Hello, how can I help you today?

USER: Due to an emergency meeting, I want to change my reservation. Can you help me with t?

ASSISTANT: Sure, please wait a moment.

USER: OK.

ASSISTANT: Sorry to say, no flight found with your requirement.

USER: No problem.

ASSISTANT: Thanks for reaching us, have a good day.

USER: Thank you.