You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Actually, I want to change my existing reservation which is done recently due to some health issues, can you please help me?

ASSISTANT: Just a moment please.

USER: Sure, I will wait.

ASSISTANT: May I know name please.

USER: Sure, my name is Anthony Davis.

ASSISTANT: I am sorry no reservation found on your name.

USER: Ok, that's fine. Anyways, thank you for your service.

ASSISTANT: Thank you.