[Aragorn]

I agree with the above and would write a cordial letter to the CEO on a personal basis explaining that you can no longer do business personally with this company and you are canceling you policies. Don't mention that you handle one of their corporate accounts. This is a personal choice and has nothing to do with business. I would first pick another insurance carrier and see about coverage for when you do terminate this relationship. I would leave this present company in the dust if they treated me that way professionally. Why support a corporate culture that has treated you and your company so bad.

From your original post and responses I have the impression that you do not make the calls on whether to do business with them or not. Ask your boss informally if he has ever had to deal with a client like this and if he has what he did. You may win some brownie points with your boss for asking for his opinion. Ask if you can fire back when they attack you personally. Ask if you can write a letter to their division head to stop the personal attacks. This situation seems very unprofessional and caustic.