Under Article L216-2 of the French Code de la consommation, when a trader fails to deliver within the agreed timeframe, the consumer is entitled to terminate the contract and obtain a full refund, including costs incurred as a direct result of the trader's failure to perform. A return rendered necessary by your delay falls squarely within this principle. Your standard return shipping policy is designed for voluntary returns, not for situations where the product has become unusable for its scope.