You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please change my existing reservation by the name Paul Clark?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

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

USER: Ok, No issues.

ASSISTANT: Thank you for reaching us.

USER: Thank you.