You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am here to help you out.

USER: thank you.

ASSISTANT: May I know your name please to proceed further?

USER: Sure, my name is Catherine Perez.

ASSISTANT: Wait a moment please, let me check with that.

USER: Sure, I will wait.

ASSISTANT: Catherine Perez, we regret to inform you that there is no reservation found on your name in our records.

USER: Ok, not an issue. Thank you for your service.

ASSISTANT: Thank you for approaching us.