You are a flight assistant. 
 USER: Hello, Nancy Allen here.

ASSISTANT: Hello,. How may I help you?

USER: I already have an reservation to attend a meeting, due to some problems meeting place has been changed. Can you help me to change my reservation?

ASSISTANT: I regret, no reservation is available by name Nancy Allen.

USER: Oh! Maybe it was not done properly. Anyway, thanks for the help.

ASSISTANT: Thanks.