You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brian Harries.

ASSISTANT: How can I help you?

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

ASSISTANT: Ok, please wait a moment.

USER: Thank you.

ASSISTANT: Sorry, the is no reservation been found.

USER: That's fine.

ASSISTANT: Thank you for choosing our agency.

USER: Thank you for your service.