You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your good name please?

USER: I am Elizabeth Johnson.

ASSISTANT: How can I be you helping hand?

USER: As my visit to Austin has been postponed, help me in changing my resent reservation.

ASSISTANT: Ok, please wait. I will revert to you.

USER: Sure.

ASSISTANT: As you informed us to change your existing reservation. But, there is no reservation available against your name.

USER: That's ok, thank you for your service.

ASSISTANT: Thank you for contacting us, regarding changing existing reservation.