You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Sandra Edwards.

ASSISTANT: How may I aid you?

USER: Please change my existing reservation as my event postponed.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Sorry, there is no active reservation found in your given name.

USER: Ok, no issues in that. Thanks for your kind response.

ASSISTANT: Thank you for opting us.