You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can i help you for today?

USER: I want to change my existing reservation, can you please help me in this intent?

ASSISTANT: Sure, I here to aid you. Can you provide me name on which the ticket is been booked?

USER: Sure, my name is Gregory Thompson here.

ASSISTANT: Thank you. Can you please wait for a while?

USER: Ok.

ASSISTANT: Gregory Thompson there is no reservation found?

USER: That's fine. Thank you for your service.

ASSISTANT: Your welcome.Thank you for choosing us.