You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Katherine Roberts here.

ASSISTANT: How may I aid you today?

USER: I would like to change my recent reservation because my health was not good, can you help me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Ok, take your own time.

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

USER: It's ok, thank you for checking.

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