Medical Insurance Payout Loophole

I have a wife who suffers from lupus and renal failure. We carry two different types of insurance, and in the past have had three. Although current with having paid needed premiums, we are frequently sued for medical bills denied by the insurance companies. When being sued or trying to determine why the insurance companies denied claims, we are faced with the impossible task of trying to dechifer cryptic billing codes that cannot be interpreted by a lay person and or by a court. Thus, you are left with, "Well, you know the bill is your responsibility". In addition, these companies rotate between being primary and secondary. We have had claims denied because both insurance companies are declaring the other to be primary. The consumer should never be in the middle of this as they end up the loser by having to unfairly pay both the premiums and the medical bills.