You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist 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'll help you with this. Please let me know your name to check the reservation list.

USER: Kevin Walker.

ASSISTANT: Ok, give me some time.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation have been found under your name in our database to amend it.

USER: No issue. Thank you.

ASSISTANT: Thank you for approaching us.