An exporter got an order of face masks based on L/C. By preparing the cargo, he found the packing material modle A were run out. Then he used modle A+ for the rest cargo. The model A+ had better quality standard and same function. However, the opening bank refused payment later by arguing that the models of packing material shown on the documents was not in accordance with that in the L/C. 1. Is it reasonable to refuse the payment? 2. What should the exporter do when he prepared the cargo?