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 Richard Baker.

ASSISTANT: Please give me a moment to check your ticket status.

USER: Sure.

ASSISTANT: Sorry Richard Baker, no reservation is available by your name.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.