付款谈判中....(求高手出谋献策)

目前有个客户订单已经下来了，价格，货期都已经谈妥。恰好最关键的一点到最好才跟他谈，就是付款方式。我发了个PI，PI款方式是30% deposit, the balance amount payment before shipping. 那个客户就来了句Didn't you understand Letter of credit will be my idea ？Pls confirm。这个客户是我一次合作的。由此看来客人就是要L/C了。于是我就找出口公司去，找的事容易搞定。但是公司要去申工厂才会受理。刚好我找的这工厂是小作坊的，很多资料是不具备的。所有目前是不了L/C。接着我复了客人那邮件，如下。Regarding to terms of payment-We regret being unable to accpet L/C beacuse of our company policy. Generally we make the terms of payment with our other customers is that 30% deposit in advance which ensure take action to order the bulk materials and bulk prodcution, and the balance 70% before shipping. 过了2天客人都没有复我邮件。于是2天后我7/3h号再出了个邮件去跟进。如下In regard to the last mail I sent to you, I thought over the matter and I also thought over your position very carefully before I make a decision. I know our both parties wish we can cooperate with each other very well and hope everything goes well. As you know we both??he no divergence except for the payment terms. I suggest it's better to further discuss this issue.To be honest, if you still insist L/C,I think it is difficult for us to proceed the matter ,besides L/C will cost a lot of time,in order to reach agreement on the payment terms, I suggest we both should make a concession step.30% deposit,the balance of 50% payment should be paid before shipping ,the left 20% payment should be paid againt the copy of B/L ,this our biggest concession.What do you think? Pls let us know your idea. We are waiting your reply ,I hope we can receive your reply soon. 7/4号客人还没有回复我，接着怎么样去跟进此事比较好？？