You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: Can you help me change my existing reservation which was made on the name of Barbara Taylor?

ASSISTANT: Sure, Please wait a while.

USER: Sure.

ASSISTANT: Thanks for your time. We didn't found any reservation by this name.

USER: That's fine, thank you for the information.

ASSISTANT: Thank you for choosing us.