You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I aid you?

USER: I am Matthew Baker. I want to change my existing reservation due to my exam scheduled has been postponed, can you please help me with that?

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

USER: Ok.

ASSISTANT: Thanks for being waiting. We didn't found any reservation by this name.

USER: Ok, no issues. Thanks for your service.

ASSISTANT: Thank you.