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

ASSISTANT: Hello, how could I support 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 for some time. There is no existing reservation find on your name.

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

ASSISTANT: Thank you for approaching us.