You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Rebecca Evans.

ASSISTANT: How can I help you today?

USER: I would like to change my existing reservation, due to health issue. Can you help me out?

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Sure.

ASSISTANT: Sorry Evans, no reservation found on your name.

USER: Not an issue. Thank you for your kind help.

ASSISTANT: Thank you for choosing us.