You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Sandra Clark.

ASSISTANT: How may I help you?

USER: I need to change my existing reservation as my bank exams got postponed, Can you please help me with that?

ASSISTANT: Sure, please hold on. I will check in the reservation list and let you know the current status.

USER: Sure.

ASSISTANT: Thanks for holding on, there is no active reservation found on your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thanks for approaching us, hope to serve you again.