You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: Myself Brenda Roberts from Washington. I want to change my travel dates in my previous reservation. Can you please help me with that?

ASSISTANT: Sure, please allow me a moment.

USER: Ok, thank you for your positive response.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes.

USER: Oh! It's ok no problem. Thank you for your information.

ASSISTANT: You are welcome, have a great day.