You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Gary Walker, here. I want to change my existing reservation due to heavy snowfall in HOU.

ASSISTANT: Give me a minute, let me check the reservation details.

USER: Sure.

ASSISTANT: Sorry Gary, there are no reservations found on your name.

USER: That's ok, thanks for your information.

ASSISTANT: Welcome.