You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello,.

USER: I am Ronald Smith.

ASSISTANT: How may I assist you now?

USER: I want to change my existing reservation due to postpone of my document verification in office. Can you help me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: Thanks for your time.

USER: Ok.

ASSISTANT:  I have checked in reservation list to change your details, but could not find any reservation with your name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thanks for opting us. Hope to serve you again.