You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Mary Campbell.

ASSISTANT: How can I help you today?

USER: would it be possible to change my reservation?

ASSISTANT: Sure, I will help you with that changing reservation. Please hold for a while.

USER: Ok, take your time.

ASSISTANT: Sorry to say that, there is no active reservation found with your name to change it.

USER: That's ok, thank you.

ASSISTANT: Your are welcome, thank you for reaching us. Have a great day.