Put the word in gap 5.Online shopping has increased dramatically in recent years as more and more people use the Internet to (1) ________ travel tickets and buy goods. However, there can be problems when buying online. Some retailers have found it difficult to guarantee (2) __________ times: goods may arrive late or not at all, Some customers become frustrated when they are unable to cancel an order or get a (3) _________ for goods they don't want. Companies that try to (4) _________spending on customer service may find it difficult to (5) _______ all the complaints from (6) ___________ customers.