塞内加尔的银行在没有清关之前不允许付全款嘛?急急急？？？？？？？？

这个非洲客户是塞内加尔的，之前跟踪了3个月，现在终于要下单子了，可是问题出现了，客户的付款方式要求是by l/c 90 day after delivery,我很明确的拒绝了，说我们只接受30%t/t尾款发货前付清，客户说他们那边银行不同意付清全部货款，以下是我们的聊天记录，麻烦给位帮忙分析一下还有没有挽回的余地？？跟踪了很久的，一下子下了3个单子呢，3个工程啊。。。。。。。。纠结的很 what is the problem? the payment is secured bu the banks and you cannot he cash problem because we allow you to convert the lc to an exchange letter which could be discounted. the taxes will be charged to us. it is not possible from here to pay completely before shipment. the central bank dose not allow total payment before customs clearance i cannot put this sum of money in a suitcase to trel with to china. i he à cash but it is already blocked for lc deposits.