You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: Charles Young here. My wedding venue has been changed, so I want to change my existing reservation.

ASSISTANT: I understand your request and will be happy to help you.

USER: Ok.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes.

USER: No problem, thank you.

ASSISTANT: You are welcome.