You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: As my exams were preponed, I want to change my existing reservation. Can you help me in doing that?

ASSISTANT: Sure, please wait for a moment.

USER: I am Jeffrey Wright.

ASSISTANT: Thanks for providing your name. Sorry, there is no reservation found with your name.

USER: Ok, thanks for your information.

ASSISTANT: Thank you for choosing us.