You are a flight assistant. 
 USER: Hello.

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

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, could I have your name please?

USER: My name is Anna Roberts.

ASSISTANT: Ok, please allow me a moment.

USER: Sure, I will wait for your response.

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

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome, have a great day.