You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Rachel Wilson.

ASSISTANT: Wilson, how can I assist you?

USER: Actually, I am planning to change an existing reservation because my I meet with an accident.Can you help me out?

ASSISTANT: Sure, I can help you to change your reservation. Sorry, no reservation found by your name.

USER: That's fine. Thank you for your help.

ASSISTANT: Thank you for contacting us.