... file a complaint with the State Insurance Department.

Even better, complain to your local congressman. Complaints from Senators/Congressmen get priority attention at the Insurance Dept. Insurance companies won't blow off Inquiries from the Insurance Dept as they might from an individual insured.

Lastly, I should say that Allstate has a good reputation. They don't, as a rule, screw insureds (something which can not be said for many, mostly smaller, insurance companies).