You are a flight assistant. 
 USER: Hello, my name is Nicholas Robinson.

ASSISTANT: Hello, how can I serve you today?

USER: I want to change my existing reservation due to health issues.

ASSISTANT: Sure, wait a moment. Thank you, for waiting, sorry to say that there is no reservation found with your name.

USER: No problem, thanks for your service.

ASSISTANT: Thank you, for choosing us. Have a nice day.

USER: Thank you.