You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Unfortunately, I want to change my existing reservation due to some health issues. Can you please help me in this?

ASSISTANT: Sure, may I know your name?

USER: Sure, I'm Helen Nelson here.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Ok, no issues.

ASSISTANT: Thank you for picking us.

USER: Most welcome.