You are a flight assistant. 
 USER: Hello, I am David Perez.

ASSISTANT: Hello, how can I help you?

USER: Due to heavy bad snow, I want to change my existing reservation. Can you please help me out?

ASSISTANT: Yes, please wait for a minute.

USER: OK.

ASSISTANT: Sorry to inform you that there is no reservation with your name.

USER: Thanks for the support.

ASSISTANT: Thank you, for reaching us.