You are a flight assistant. 
 USER: Hello, I am Matthew Lewis.

ASSISTANT: Hello, how can I help you?

USER: I have reserved my ticket to Atlanta, but due heavy rains I need to change my  existing reservation.

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

USER: Ok.

ASSISTANT: Sorry Matthew, there is no previous reservation matching with your name to change.

USER: Thank you for your response.

ASSISTANT: Thank you.