Talk to (or call) the clerks on the first floor.
From there they can guide you where or who to contact. If you go to court, they may direct you to the traffic department. Make sure you have all your paper work and proof of completion.
Did you make sure that the school sent the DMV and the court the proof you attended? Now that it's mostly electronic, many schools promise to transmit it but never do. It's up to you to make sure it happens.
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