Your file was just placed on my desk for disposition¹. It seems that your account is seriously past due. We have valued your business for many years， and can only hope that this lack of payment is only an error or an oversight². If you have mailed your check， thank you. If not， please advise this office if any discrepancy³ exists. I have reviewed the account， and feel I must advise the management to cancel existing credit lines unless payment is received within ten days.

　　I understand that you have had problems lately， and feel that we have been most accommodating. Accordingly， I will expect your check no later than