You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you?

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

ASSISTANT: Sure, please wait for a moment.

USER: Sure, I will wait for your reply.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: That's fine.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your service.