You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for today?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: I am happy to help you about that. Can you please provide your name for checking the reservation status?

USER: Sure, my name is Christine Gonzalez.

ASSISTANT: Please wait for a while I will check in our booking list. Sorry Christine Gonzalez, there is no active reservation with your name for changing your reservation.

USER: That's fine, thank you for your service.

ASSISTANT: You are welcome, thank you for reaching us.