You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Pamela Perez.

ASSISTANT: How may I be of your help?

USER: I want to change my existing reservation, please help me out.

ASSISTANT: Sure, I'll help you in change an existing reservation. Ok, please wait a moment.

USER: Thank you. Ok, I will wait.

ASSISTANT: Thank you for waiting, sorry to inform you that there is no reservation found by your name.

USER: No problem, thanks for the response.

ASSISTANT: Thank you for approaching us.