You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. In which way I can assist you right now?

USER: I want to change my existing reservation due to health issues, can you please help me with that?

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Can I know your name please?

USER: My name is Alexander Williams.

ASSISTANT: Please wait a moment to check.

USER: Sure.

ASSISTANT: We regret to tell you that, there is no reservation found on your name in our records.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us, have great day.