You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Myself Amanda Clark.

ASSISTANT: How can I help you?

USER: Due to some health issues, I want change my existing reservation. Can you help me?

ASSISTANT: Sure, I will you help with. I am sorry  no reservation found on your name Mr.Amanda Clark.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us.