You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How could I serve you today?

USER: Stephanie Lewis here. I need to change my existing reservation as my plan to go for an historical tour got postponed. Can you please check if my reservation is active or not? If it is active, please change it.

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Unfortunately there is no reservation found with your provided name in our data base.

USER: Ok, not an issue.

ASSISTANT: Thank you for opting us.

USER: Thank you for the information.