You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Anna Martin. I want to change my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I can help you with changing. Please allow me a moment. Thank you for waiting, I have checked and it is showing that there is no reservation found for the user name in our back end.

USER: That's ok, thank you for checking.

ASSISTANT: You are most welcome and thank you for reaching us.