Humana Healthcare Tricare Prime for Retired Military Cancels my healthcare from Prime to not eligible for healthcare Louisville Kentucky

Humana terminated my healthcare Prime twice although I have paid my monthly service charges.  Humana website allows you to make additional payments and also allows you to over pay the monthly charge.  I have on two occasions overpaid them although my monthly payments are paid.  Because I went to my bank (VISA) to get back the addiontal 2 over-payments, Humana says I am behind in payments although my bank Visa statements show my monthly payments.  I have discussed this with Humana over ten times in past three months they have decided to take my heathcare Prime away making it so difficult to control and be within specific parameters of Prime.  Then my in network doctors cannot get paid so they come after me.  Humana denies my overpayment and feels the extra money over paid is thiers.  They have continually denied my claim for over paid money and has not  addressed my issue shown in my Visa statements sent.  I am thinking of getting an attorney to fight this.  Does anyone know how I should proceed.  I am working with NFCU Visa department and they have agreed in my favor that these are over paymernts (2 of them) as the monthly payments were up to date as of March 2015.