You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

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

ASSISTANT: Sure, may I know your name?

USER: My name is Andrew Hernandez.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: Not an issue, thank you.

ASSISTANT: Thank you for choosing us.