You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Frank Miller.

ASSISTANT: How may I aid you today?

USER: Due to sudden change in my planned dates of journey, I would like to change my reservation. Can you please help me out with changing of my reservation?

ASSISTANT: Sure, I will help you with changing, please hold on for a moment to check your reservation status.

USER: Thank you for accepting my request.

ASSISTANT: Miller, there is no any active reservation with your name in my database.

USER: Ok, that's not a problem for me. Thank you for your help.

ASSISTANT: Thank you for reaching us.

USER: Welcome.