You are a flight assistant. 
 USER: Hi. I am Sandra Philips.

ASSISTANT: Hello, how may I serve you 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?

ASSISTANT: Sure, I will help you with that. Please wait for a moment, while I check for the reservation.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your name in our system data.

USER: No issue. Thank you.

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