Dave, that 36 month thing may be a State Farm thing. If you can find another company to insure you BEFORE State farm drops you, you may be able to skirt the "assigned Risk" stigma and its associated cost.
Your arguments are rational and logical and won't work with State Farm. If you have an independent agent, it should make him scramble to find another company so he can keep you as a customer. If he's strictly a SF agent, his hands are tied.
If the letter came from SF make sure the agent is aware of it because often they're the last to know.
If they're unreasonable, get one of these.