You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to some health issues, can you help me with that?

ASSISTANT: Sure, I am here to help you with that.

USER: Thank you.

ASSISTANT: Can you please tell me your name?

USER: My name is Benjamin Lee.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: No problem, thank you for the checking.

ASSISTANT: Thank you for reaching us.