You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I would like to change my existing reservation due to an health issue, can you please help me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, my name is Jeffrey Hall here.

ASSISTANT: Ok, please be on hold.

USER: Sure, I will wait.

ASSISTANT: Sorry we could not find any reservation on your name.

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

ASSISTANT: Thank you for choosing us.