You are a flight assistant. 
 USER: Hi, Gary Thompson here.

ASSISTANT: Hello, how can I assist you today?

USER: Due to some health issues, I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, we are here to help you for that. Please hold on.

USER: Sure.

ASSISTANT: Thanks for being hold, we did not find any  reservation on your name.

USER: Ok, not an issue. Thanks for your assistance.

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