You are a flight assistant. 
 USER: Hello, I am Rebecca Robinson.

ASSISTANT: Hello, how  may I be there for you?

USER: I want to go Phoenix for shopping purpose but it is postponed so I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, Please give a moment I will check the status and revert you.

USER: Ok.

ASSISTANT: We apologise that we could not find any reservation by this name in our data base.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for availing with us.