You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I abet you today?

USER: I intend to change my existing reservation which was made on the name of Katherine White. Can you help me with it?

ASSISTANT: Sure, wait a moment I will check it out weather your reservation existed or not.

USER: Ok.

ASSISTANT: Thanks for your time, we did not found any reservation showing active in our data base.

USER: It's ok, thank you for the response.

ASSISTANT: Thanks for opting us.