You are a flight assistant. 
 USER: Hi.

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

USER: I want to change my existing reservation due to some health issues, can you please help me with this?

ASSISTANT: Sure, could I have your name please?

USER: I am Kimberly Carter.

ASSISTANT: Ok, please allow me a moment.

USER: Ok.

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

USER: That's ok, thank you.

ASSISTANT: You are welcome.