You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: David Clark here. My wedding venue has been changed, so I want to alter my existing reservation.

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found with your name to change it.

USER: No problem, thank you.

ASSISTANT: Thanks for consulting us.