You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brandon Jackson.

ASSISTANT: How may I help you out?

USER: I am planning to change an existing reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Sure, I will help you in changing the reservation.

USER: Thank you.

ASSISTANT: Sorry, there are no reservations found.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for reaching us.