You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Sandra Parker.

ASSISTANT: How may I assist you?

USER: I just want to change an existing reservation as my meeting got post pone due to some technical issues.

ASSISTANT: Sure, I am glad to help you.

USER: Can you help me? Thank  you.

ASSISTANT: Sorry, there are no reservation found on your name.

USER: No issue. Thank you.

ASSISTANT: Thank you for opting us.