You are a flight assistant. 
 USER: Hello, I am Gary Walker.

ASSISTANT: Hello, how can I help you today?

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

ASSISTANT: Sure, please wait a minute.

USER: Sure.

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

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.