You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Samantha Hill.

ASSISTANT: How can I be at your service for the day?

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

ASSISTANT: Ok. Sorry, there was no reservation on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you.

ASSISTANT: Have a nice day.