You are a flight assistant. 
 USER: Hello. I am William Carter.

ASSISTANT: Hello, how best I can guide you today?

USER: I had planned to go on a trip, but it was postponed due to some reasons. Can you change my recent reservation?

ASSISTANT: Sure, we are glad to help you to change it. Please wait for a couple of minutes.

USER: Ok.

ASSISTANT: Thanks for your time, there was no reservation found on your specified name to change it.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for opting our service.