You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: I am Brandon Parker. I want to change my reservation, due to health issue. Can you help me out?

ASSISTANT: Sure, please give me a moment.

USER: Sure, take your time.

ASSISTANT: Unfortunately, there is no reservation exist to proceed further.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for consulting us.