You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I help you?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, May I know your name?

USER: Rachel Clark.

ASSISTANT: Please wait a second.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name.

USER: No issue. Thank you.

ASSISTANT: Thank you for opting us.