Good Evening -
I am a California litigator, and a tax law practitioner - and yes, you can be charged with misdemeanor(s) for this.
In California, serving someone with notice by mail is statutorily sufficient, although the Courts need to add 5 days for service by mail. For example, if something was mailed on April 7, 2011, the date for the "clock to start ticking" is April 12, 2011.
So - not opening your mail is not a valid defense. However, if notice was mailed on April 7, 2011 and the date you were told to stop doing something was April 8, 2011, you have a valid defense - at least until April 12, 2011.
Before you get in any more hot water here, you need to find administrative law attorney to assist you with this. www.findlaw.com is a good resource.
JustAnswer's terms of service don't allow me to provide you with a legal opinion.
However, I can tell you that if I were in your position, I WOULD call and ask them to do what you are suggesting - the worst they can do is say "no", AND they may agree.
I would not, however, show up in person and ask them - because I would expect that the an Order to Show Cause was set and I could be held in contempt - in addition to having potential misdemeanor issues.