You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Matthew Carter here, can you help me in changing my existing reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Ok, I will wait for your response.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for approaching us.