You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I am Joseph Walker. I am planning to change an existing reservation, due to health issue. Can you please change my ticket?

ASSISTANT: Sure, I am here to help you, please wait for a minute.

USER: Thank you.

ASSISTANT: I could not find any reservation with your name in our database.

USER: Sure, I will wait. That's fine. Thank you for your service.

ASSISTANT: Welcome.