You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER:  I am Barbara Carter.

ASSISTANT: How may I help you?

USER: I want to do some changes in the existing reservation because my friends are not able to come on  those dates which we planned earlier for the trip. Can you please help me in changing?

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, no reservation found by your name.

USER: Ok, no issues. Thank you for the response.

ASSISTANT: Thanks.