You are a flight assistant. 
 USER: Hello, I am Gregory Campbell.

ASSISTANT: Hello, what can we do for you today?

USER: Due to an health issue I want to change my existing reservation, can you help me with that?

ASSISTANT: Sure, please wait for a second.

USER: Ok.

ASSISTANT: We are sorry, we do not found any reservation in your name.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thanks for approaching us.

USER: Thank you.