You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I render you at this moment?

USER: I am Sharon Hernandez. I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Sure, please wait for few minutes.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name for the modification.

USER: Not an issue, thanks for your help.

ASSISTANT: Thank you for opting us.