You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: Helen Thomas 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 help you. Please hold a moment.

USER: Ok, I will wait.

ASSISTANT: Thank you for your time, sorry no reservation found with your name.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for availing us.