You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

USER: Andrew Davis here. I would like to change my reservation due to some health issues, can you please help me with that?

ASSISTANT: Sure, I will aid you. Please wait for a moment, I will check your reservation details in our records.

USER: Thank you for accepting my request. Sure, take your time.

ASSISTANT: Sorry, there is no reservation existing on your name.

USER: That's ok, no problem. Anyway thank you for checking out.

ASSISTANT: You are welcome, have a nice day.