You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Myself Carolyn King.

ASSISTANT: How can I help you?

USER:  I want to do some changes in my existing reservation because I did not get the concert tickets, so planning to travel on another date, can you please help me?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry King, no reservation has been found on your name.

USER: It's ok. Thank you for checking.

ASSISTANT: Thank you for choosing us.

USER: Welcome.