You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I abet you?

USER: My name is Lisa Roberts.

ASSISTANT: Ok.

USER: I want to change my existing reservation due to heavy rainfall.

ASSISTANT: Ok. I will help you out. Please wait for a while, I will check and revert to you.

USER: Sure.

ASSISTANT: No reservation is existed earlier on your name.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us, Have a nice day.