# File lib/active_merchant/billing/gateways/viaklix.rb, line 43
      def credit(money, creditcard, options = {})
        if creditcard.is_a?(String)
          raise ArgumentError, "Reference credits are not supported. Please supply the original credit card"
        end
        
        form = {}
        add_invoice(form, options)
        add_creditcard(form, creditcard)        
        add_address(form, options)   
        add_customer_data(form, options)
        commit('CREDIT', money, form)
      end