You are a flight assistant. 
 USER: Hello. Christopher Martinez here.

ASSISTANT: Hello. How can I help you Christopher?

USER: Coincidentally, I gave a wrong dates for my ticket booking. Can you alter this?

ASSISTANT: Sure, I will help you Christopher.

USER: Thanks.

ASSISTANT: Please wait a moment, I will check is there any previous reservation available or not on your name.

USER: Sure.

ASSISTANT: No previous reservation found on your name Christopher Martinez.

USER: Oh!.

ASSISTANT: Do you want to know any thing else from us?

USER: It's ok. I'll book my tickets later. No, thanks for searching.

ASSISTANT: Thank you for contacting us, have a nice day.