You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know your good name?

USER: My self Catherine Collins.

ASSISTANT: What can I do for you Catherine?

USER: I would like to change my existing reservation due to sudden change in my trip.

ASSISTANT: Ok, please hold on I will check and get back to you.

USER: Ok.

ASSISTANT: Thanks for your time. There is no reservation found on your name.

USER: Thank you for your information.

ASSISTANT: Thanks you for reaching us.