You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for the day?

USER: Due to my health conditions, I want to change my recent reservation.Can you help me with that?

ASSISTANT: Sure, I am here to help you with that changing reservation.

USER: Thank you.

ASSISTANT: Can I know your name please for checking your previous reservation status?

USER: Janet Thomas here.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found on your name in our database to change it.

USER: No problem, Thanks for the information.

ASSISTANT: Thank you for reaching us. Have a great day.