You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Catherine Collins here.

ASSISTANT: How best can I guide you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, please stand by a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, there is no active reservation found with the given name.

USER: Not a problem. Thank you.

ASSISTANT: Thank you.