13. We would also accept a certified check as well as a direct bank remittance.
我们也接受保付支票或是银行直接汇款。
还能这样说：
Either certified check or direct bank remittance is all right.
We accept payment by certified check or direct bank remittance.
应用解析：
powerful check to sth. 对……有力的控制；
under proper checks and restraints 在适当的控制之下；
suffer a check 受挫

14. Payment might be refused if anything goes wrong with the documents.
如果单据有问题，可以提出拒付。
还能这样说：
We approve of refusal of payment if anything goes wrong with the documents.
Under the circumstance that the documents go wrong, we will allow the buyers refuse to pay.
谚语：
Losers are always in the wrong.
胜者为王，败者为寇。

15. It would help me greatly if you would accept D/P.
你如果能接受付款交单的话，会对我有很大帮助。
还能这样说：
It would be greatly helpful if you would accept D/P.
It would benefit greatly if in case that you accept D/P.
应用解析：
accept sb.'s good will 接受某人的好意；
accept sb.'s hand in marriage 答应与某人结婚；
accept sb.'s reasons 相信某人的理由

16. Payment is to be made before the end of this week.
这个周末以前应该付款。
还能这样说：
You have to pay before the end of this week.
The deadline of the payment is this weekend.
应用解析：
this day week 一星期后的今天；
week after week 一个星期接另一个星期，一连数周；
week in week out 每个星期都，毫无例外；
every other week 每隔一周

17. We may have some difficulties making payment in pound sterling.
用英镑付款可能会有困难。
还能这样说：
It may be difficult to pay by pound sterling.
We have trouble to choose pound sterling as the means of payment.
应用解析：
make a difficulty 刁难，找麻烦；
iron out difficulties 除去障碍，使事情圆满