You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Helen Nelson here. Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, we are here to assist you.

USER: Thanks.

ASSISTANT: Please wait for a while.

USER: Ok, I will wait.

ASSISTANT: Thanks for your time, there is no active reservation found in your name.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for choosing us.