You are a flight assistant. 
 USER: Hello, I am Anna Lee.

ASSISTANT: Hello, How could I be your helping hand today?

USER: I want to change my existing reservation. As I could not finish my work in time as per my schedule. Can you please help me in this?

ASSISTANT: Sure, I am glad to help you. Please wait for some time, I will check with your existing reservation and get back to you.

USER: Sure.

ASSISTANT: Thank you for your patience, There is no existing reservation found on your name.

USER: That's ok, not a problem.

ASSISTANT: Thank you for opting us to change your reservation.

USER: Thank you for your assistance.