You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I render you?

USER: I am Rebecca Miller. Can you please change my existing reservation? Because the doctor appointment was postponed to other days.

ASSISTANT: Sure, we are here to help you. Wait for some time I will check the reservations on your name.

USER: Thank you. Sure.

ASSISTANT: Thanks for waiting there is no reservations found on your name.

USER: Ok.

ASSISTANT: Thanks for approaching us.

USER: Thanks for the information.