客户说以前的产品质量差，怎么说服他呢

到一封询盘，葡萄牙的客户J发的，产品规格说的都挺详细，然后报价后，客户要求我三个欧洲客户的信息，具体交流如下，大虾们帮帮忙，我该怎么说服他我们的产品呢？ Hi C Please send references of end users who use your prudct. Not recent ones. Please choose ones with more than 3 years experience. Please also inform name of the companies your international customers are using for local quality control Best regards 然后我回复的邮件也是福步里看过来的 Hello , We he end user in North America to distribute our product, but I'm not permitted to tell their information to you because of trade secrets and professional ethics. Hope you can understand. If you're afraid of quality, I'd like to help you to know our product well, sample can be provided for testing. Hope it will be useful to your business. Best Regards, 之后客户就一直不回复我，发过去好几封骚扰信，最后一封讲了下产品的优势，客户就回了 Hi C Without an opinion of at least 3 European senior companies I’m not interested in going further. Thank you 我回复 Hi J Thanks for your clear reason. However, I don't agree with you, we should pay more attention on the natural: what is really wanted???Good quality! 3 European senior companies required is not necessary, we're a developing factory manufacturing XX, with strength to he a larger exporting market.??FREE SAMPLE provided can prove it. Trial order is also appreciated. Moreover, our price is more competitive than other China suppliers with little profit, cause we value you as our important customer. Hope an opportunity can be offered, you will feel our professional service. Thanks&Regards 客户的最后一封回复 C I’m very sorry not trust in your personal opinion and probably I’m losing a good opportunity, but I had very big problems in EVERY ITEM import from China. From now on I do not buy nothing made in China without being advised by three well recognized??European Companies Best regards 我觉得这个客户还是可以被说服的，就是不知道接下来还可以说什么了，客户还是一直有回复我还挺欣慰的，希望高手能够帮忙下，接下来该怎么回复呢