You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I would like to do some changes in my existing reservation due to some issues, can you help me in that?

ASSISTANT: Sure, may I know your name please?

USER: Sure, the ticket has been reserved on the name Rebecca Williams.

ASSISTANT: Sorry, there was no reservation found with your given name.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for choosing us.