For all intents and purposes, your employer has: 1) committed fraud; 2) committed theft; 3) become your insurance company; 4) in hot water. You might consider a number of steps: making a complaint to the prosecutor's office, bring a law suit, seek civil theft damages, and so forth.
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This may be either a very serious problem involving taking of funds inappropriately OR may be an accounting error in taking funds beyond a date when they should have been taken. Either way you need to begin by contacting your employer and finding out what their position is with regard to the situation. Either way you would be entitled to, at least, the return of the premiums wrongfully deducted with interest imputed by law. If you incurred expenses that should have been paid by these insurance coverages, the matter gets more complicated. Your employer may be responsible for the bills incurred up to the amount of insurance coverage that would have applied. You should seek the assistance of an attorney to properly protect your rights.