You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Gregory Hall.

ASSISTANT: Welcome to Global flight booking agency, how may I help you?

USER: Due to the heavy rains in my visiting city, I want to change my existing reservation.

ASSISTANT: Ok, Gregory. Please hold on a minute.

USER: Ok.

ASSISTANT: Thank you for your patience, there are no active reservations found with your details.

USER: Ok, that's not a problem. Thank you for your support.

ASSISTANT: Thank you for choosing our agency, Gregory Hall.

USER: Welcome.