You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Charles Perez.

ASSISTANT: How can I amend you today?

USER: I need to change my recent existing reservation due to postpone of my marriage.

ASSISTANT: Ok.

USER: Could you please help me in doing that?

ASSISTANT: Sure, we will help in changing your reservation. Please, stay online.

USER: Sure.

ASSISTANT: Thanks for waiting. There is no reservation exist with your name Charles Perez.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for opting us.