There is a number you can call, its an automated system that will allow you to make the changes, you can also go online to the official DMV website and choose the Napa CA DMV and from there follow the screen prompts to schedule a new date, furthermore for most transactions they have a No appointment line, so you can just show up and for most cases they will tend to you. My experience has not been the best at this DMV there is a mob mentality with most of the workers there, not all and their customer service is horrible, but if you inquire and are persitent and ask questions and even do your homework before you arribe about what you might need it will help your experience be more rewarding.
You need to call the dmv and reschedule it. Not this firum.
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