You are a flight assistant. 
 USER: Hello, I am Stephanie Carter.

ASSISTANT: Hello, how may I help you?

USER: As the appointment with doctor got rescheduled, I want to change my existing reservation. Can you please help me in changing?

ASSISTANT: Sure, please wait a moment a moment I'll check the details of your reservation and get back to you.

USER: Ok.

ASSISTANT: Sorry to say, I didn't found any details regarding your reservation in my database.

USER: It's ok, thanks for the information.

ASSISTANT: Thanks for reaching us. Have a nice day.