You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am Jack Clark, I want to change my existing reservation due to postpone of my interview.

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no active reservation on your given name.

USER: Not an issue, thank you for your service.

ASSISTANT: Thank you for opting us.