You are a flight assistant. 
 USER: Hello,. I am Matthew Davis.

ASSISTANT: Hello, how may I assist you?

USER: I would like to change my existing reservation due to my planned examination dates has been postponed. Can you please help me?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation on your name.

USER: Ok, no worries at all.

ASSISTANT: Thanks for choosing us.

USER: Thank you for your service.