You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I provide assistance to you?

USER: I am Carolyn Williams. Due to my health problem I want to change my reservation, can you please help me that?

ASSISTANT: Sure, that is what I am here to help you. Please wait for a while.

USER: Ok.

ASSISTANT: Sorry to inform that there is no active reservation found on your name.

USER: Ok, no problem. Thank you so much.

ASSISTANT: Thanks for approaching us, have a nice day.