You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Frank Williams.

ASSISTANT: Frank, How can I aid you today?

USER: I need to change my reservation as my exams got postpone to another date. Can you please help me in changing?

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting. Sorry to say that, there is no active reservation found with your name, to change it.

USER: Ok, thank you.

ASSISTANT: Thanks for your approach.