You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation due to prepone of my plans. Can you please help me in that?

ASSISTANT: Yes, can you share me your name?

USER: Michael Gonzalez here.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you.