You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, please provide me your name to check the reservation?

USER: I am Nicole Johnson.

ASSISTANT: Sorry, there is no reservation with your given name.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us.