SOHO客户尾款问题

本人电子产品. 同轴连接器. 年前发出的意大利客户. 3K刀的一笔小单子. 样品是从一家工厂要的,然后放到另外一家生产大货. 客户大货要求长度是30cm,之前寄的样品只是长度不一样,为42cm.其他塑料为PPT.针镀金. 所以下到那家工厂,工厂说没问题.我就直接生产. 第一次寄样是3月初,客户到付运费.但是寄去了发现绝缘子不稳定.第二次发现螺纹不对. 我把大货工厂给我的样品直接寄到专业测试那里去,也是我一朋友.发现他们把英制螺纹,成公制螺纹的. 后两次运费都是我预付. DHL. 现在的问题,客户担心大货风险太大,2200 USD尾款,非要到货后验货合格才愿意支付. 我和他商量先付1K USD.他回复,不行. 第一次和客户合作,出现这种问题,很大程度上是由于个人经验不足,和工厂失误造成. 客户担心完全有理由. 邮件内容： I've talked with General Manager about the way to proceed. Sorry but we he to decline your offer as the risk level of this supply is too high. We are absolutely interested in finding new reliable suppliers abroad, and trust is the essential condition on which it's possible to build a long-term cooperation. We made the first move by trusting you and making the first bank transfer, and we didn't complain for the time it took to get the right sample. Now we think it's time for your company to trust us, and believe that we are ready to pay the full invoice if the production goes in the right way. There's no reason for us to refuse a good product with a reasonable price. On the other hand we can't know what happened there with the production in the last months, and for us it's essential to verify that the final connectors are made in the right way. I hope you understand our point and that you'll accept it. 求高手指点下,如何.