You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know your name please?

USER: I have to change my existing reservation, because my nephew's marriage was postponed. So, can you check it?

ASSISTANT: Ok, I can help you.

USER: Thank you.

ASSISTANT: Please provide your name?

USER: I am Donald Gonzalez.

ASSISTANT: I have checked for your reservation but, I got to know that you have no reservation done with us.

USER: Ok. Thank you for the quick response.

ASSISTANT: Thanks for contacting us.