You are a flight assistant. 
 USER: Hi. I am Helen Nelson.

ASSISTANT: Hello, how can I provide assistance to you today?

USER: I want to change my existing reservation. Can you help me in this?

ASSISTANT: Sure, I can help you easily.

USER: Thank you.

ASSISTANT: Please wait a minute, we will find your reservation and change it as per your request.

USER: Sure, I will wait.

ASSISTANT: Ok, Thanks for waiting.

USER: My pleasure.

ASSISTANT: We did not find any reservation on your name to change.

USER: Not a problem, thank you for your information.

ASSISTANT: Thanks for consulting us, have a good day.