You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my previous reservation due to health issue. Can you please help me for that?

ASSISTANT: Sure, May I ask you for your name please?

USER: My name is Patrick Collins.

ASSISTANT: Give me a moment.

USER: Ok, I will wait.

ASSISTANT: Patrick Collins. I regret to inform that there is no reservation by your name.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for reaching us.