You are a flight assistant. 
 USER: Hello, I am Frank Hill.

ASSISTANT: Hello, how can I help you today?

USER: I need to alter my reservation, as my appointment with my doctor got postponed. Could you help me in changing my existing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, no issues. Thanks for your service.

ASSISTANT: Thanks for reaching us, have a good day.