（1）subject: Demanding Overdue Payment
As you are usually very prompt in settling your accounts, we wonder whether there is any special reason why we have not received payment of the above account, already a month overdue.
We think you may not have received the statement of account we sent you on 30th August showing the balance of US$ 80,000 you owe. We send you a copy and hope it may have your early attention.
（2）Subject: Urging Payment
Not having received any reply to our E-mail of September 8 requesting settlement of the above account, we are writing again to remind you that the amount still owing is US$ 80,000. No doubt there is some special reason for delay in payment and we should welcome an explanation and also your remittance,
（3）Subject: Insisting on Payment
It is very difficult to understand why we have not heard from you in reply to our two E-mail of 8th and 18th September for payment of the sum US$ 80,000 you are still owing. We had hoped that you would at least explain why the account continues to remain unpaid.
I am sure you will agree that we have shown every consideration and now you fail to reply to our earlier requests for payment, I am afraid you leave us no choice but to take other steps to recover the amount due.
We are most reluctant to do anything from which your credit and reputation might suffer and even now we prepare to give you a further opportunity to put the matter right.We therefore propose to give you 15 days to clear your account,
（1）The following items totaling $4000 are still open on your account.
（2）It is now several weeks since we sent you our first invoice and we have not yet received your payment.
（3）I'm wondering about your plans for paying your account which,as you know,is now over 40 days ast due.
（4）We must now ask you to settle this account within the next few days.