You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I aid to today?

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

ASSISTANT: Sure, please wait while I check your reservation in our database.

USER: Sure.

ASSISTANT: I am sorry to inform you that no reservation has found on your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you.