# File lib/active_merchant/billing/gateways/first_pay.rb, line 50
      def refund(money, reference, options = {})
        requires!(options, :credit_card)

        post = FirstPayPostData.new
        add_invoice(post, options)
        add_creditcard(post, options[:credit_card])
        add_address(post, options)
        add_customer_data(post, options)
        add_credit_data(post, reference)
      
        commit('credit', money, post)
      end