You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I address you today?

USER: I already have a reservation to attend a conference. In Skype call conference has been completed. Can you please change my existing reservation?

ASSISTANT: Sure, please provide your name?

USER: My name is John Clark.

ASSISTANT: Thank you for your name there is no reservation found on your name.

USER: It's Ok. Thanks for your positive response.

ASSISTANT: Thank you for making us to assist you.