    # 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