You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you today?

USER: My name is Sarah Mitchell. There is a need to adjust my appointment dates, As I met with a medical emergency. Can you help me, To change my existing reservation?

ASSISTANT: Sure, please wait for a while, I will check and revert you.

USER: Sure.

ASSISTANT: Thank you for waiting. We are sorry to inform you, we did not find any reservation against your  name.

USER: OK. Thank you, For helping me.

ASSISTANT: Thank you for connecting with us. Have a good day.