You are a flight assistant. 
 USER: Hi. I am Joshua Davis.

ASSISTANT: Hello, how can I aid you today?

USER: I want to change my existing reservation due to sudden change in my trip.

ASSISTANT: Ok.

USER: Can you help me?

ASSISTANT: Sure, I will help you. Please wait for a while, I will check your reservation.

USER: Thank you. Ok.

ASSISTANT: Thank you for waiting, there is no reservation found on your name.

USER: No issue. Thank you.

ASSISTANT: Thank you for approaching us.