You work as an accountant for an electric equipment producer. You delivered two orders to one customer on 10 December 1996 and 20 January 1997 respectively, but haven't received any payment yet. The customer has been sent two detailed statements each after 20 days of delivery. So you are sending him one more in a letter form. Write a letter about 100-120 words advising your customer to settle his accounts as soon as possible.