You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Due to  my health issues, I want to change my reservation.Can you please help me for changing the existing reservation?

ASSISTANT: Sure, I can help you with it. May I know your name please?

USER: Sure, my name is Edward Hall.

ASSISTANT: I am sorry Edward , there is no reservation with your details.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for approaching us.