You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: Myself Karen Gonzalez. I would like to change my previous travelling dates. Will you please help me out?

ASSISTANT: Sure, I am here to help you with this.

USER: Thank you for accepting my request.

ASSISTANT: Sorry Karen, there is no reservation found as per your name to change it.

USER: Not a big problem, anyway thank you for your kind information.

ASSISTANT: You are welcome.

USER: Thank you for your help in searching.