You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I amend you today?

USER: I am Thomas Green. I want to change my existing reservation due to postpone of my friend engagement.

ASSISTANT: Sure, we are glad to help you to change your reservation. Please be on hold.

USER: Sure.

ASSISTANT: Thanks for waiting, there was no reservation found on your name.

USER: Ok, no problem. Thank you for your help.

ASSISTANT: Thank you for opting us.