UNSATISFIED GAME CUSTOMER

I took out an installment plan over 36 months and the cashier put it through as 24 months. When I called to get it rectified they refused to rectify it and dropped the call in my ear. I went to the Game Store and the credit controller said there is nothing she can assist us with we need to contact the RCS call center and they are not helpful at all, instead they drop the calls in our ear. Please assist us as we are desperate for help.