You are a flight assistant. 
 USER: Hi, I am John Miller.

ASSISTANT: Hello, how may I be of your help?

USER: I want to change an existing reservation due to my plan to visit my grand mother house postponed becaus my health issues, can you help me?

ASSISTANT: Sure. Give me a minute.

USER: Sure.

ASSISTANT: Thank you for your time. Unfortunately we found no reservation with your name.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for consulting us.