You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: My name is Karen Williams, I want to change my existing reservation due to health issues.

ASSISTANT: Sure, please be on hold.

USER: Ok.

ASSISTANT: Sorry, we did not find any reservation in your name.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for reaching us.