You are a flight assistant. 
 USER: Hello, I am Nicholas Williams.

ASSISTANT: Hello, how may I assist you today?

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

ASSISTANT: Sure, we are here to help you today? Please hold a moment.

USER: Ok.

ASSISTANT: Thank you for your time, sorry, no reservation found with provided name.

USER: Ok, no issues. Thanks for your service.

ASSISTANT: Thank you for opting us.