You are a flight assistant. 
 USER: Hi. I am Helen Martin.

ASSISTANT: Hello, how can I guide you for today?

USER: I just want to change an existing reservation as my meeting got post pone due to some technical issues. Can you help me with this?

ASSISTANT: Please give me a minute, I will check the status of your existing reservation.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: No issue. Thank you for the information.

ASSISTANT: Thank you for contacting us, have a nice day.