You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Nancy Perez here.

ASSISTANT: How can I assist you?

USER: I want to change my existing reservation due to my health issue, will you help me?

ASSISTANT: Sure, please let me check.

USER: Sure.

ASSISTANT: Sorry Nancy, I have not found any reservation by your name.

USER: Ok, thank you for your information.

ASSISTANT: Thank you for reaching us.