Credit memo – Refund higher then total order

My company work in Magento 1.9.2.1, the customer bought the goods (goods+ shipment to customer = order XY), the model received broken, He packed it and pay own cash for shipment back to a warehouse (amount 111) We raised Magento credit memo for full amount order XY, but we need to refund also shipping fee what customer paid back to the warehouse 111 Euro. The system doesn’t let us credit more than the customer originally paid. I am not able to credit 1 more cent than he paid for his order, but how can I refund missing shipping to the warehouse?