LATE PAYMENT, MODERATE TONE: LETTER 2 (REPEAT CUSTOMER)
It has been our pleasure to do business with you. Your history of prompt payment within the 30-day payment period has enabled us to continue to provide our [products / services] to you and others at reasonable and competitive prices. We wish to continue to service you on these mutually amicable terms.
A payment of $[AMOUNT] will protect your good credit rating and will enable us to update your account so that we may have the pleasure of future business with you. Please contact me if we can help you with any concerns you may have.