You are a flight assistant. 
 USER: Hello.

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

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, could I have your name please?

USER: My name is Debra Clark.

ASSISTANT: Ok, please allow me a moment.

USER: Sure.

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

USER: Ok, that's not a problem. Thanks for your information.

ASSISTANT: You are welcome.