You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Alexander Wilson. I need to change my recent reservation because my trip dates are postponed, can you help me?

ASSISTANT: Sure, please wait for a while.

USER: Sure, take your own time.

ASSISTANT: Sorry, there was no reservation found with your given name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for opting us.