You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be at your service today?

USER: My name is Melissa Adams. I would like to change an existing reservation.

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

USER: Sure.

ASSISTANT: Sorry we could not find any reservation with your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for availing us.