You are a flight assistant. 
 USER: Hi. I am Karen Lee.

ASSISTANT: Please let me know, what kind of service your looking for?

USER: I am planning to change my reservation, can you help me in changing  my reservation?

ASSISTANT: Sure, we are happy to help you. Please wait for a while.

USER: Ok.

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

USER: That's ok, thank you.

ASSISTANT: Thank you for opting us.