You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation which is done recently due to business meeting postponed, can you please help me?

ASSISTANT: Sure, can you give me your name for changing purpose?

USER: Ok, my name is Brian Campbell.

ASSISTANT: Ok, please be on hold, let me check for the availability.

USER: Ok, please check it.

ASSISTANT: Sorry, Campbell there is no reservation found on your name.

USER: Ok, no issues.

ASSISTANT: Thank you for approaching us.

USER: Anyways, thank you for your service.