You are a flight assistant. 
 USER: Hello, I am Christopher Lewis.

ASSISTANT: Hello,  How may I help you out ?

USER: As my sister's marriage is postponed, Can you please change my reservation?

ASSISTANT: Sure, I can change your reservation, please give me a couple of minutes to check.

USER: Sure.

ASSISTANT: I checked the status of your reservation, but I can not found your name with reservation. Thank you for approaching our service.

USER: Thank you.