You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I support you today?

USER: Please change my existing reservation due to some health issues?

ASSISTANT: Sure, we are here to help you. Could you please let me know your name to check the reservation status?

USER: Sure, I am Brain Anderson.

ASSISTANT: Ok, please wait a minute I will get back to you with the present status.

USER: Sure.

ASSISTANT: Sorry, there is no active reservation have been found under your name in our database to change it.

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

ASSISTANT: Thank you for choosing us.