What is the BEST way to proceed with a customer if you know that there will be a delay in delivering a product or service? Apologize to any customer who calls to complain about the delay, and provide an updated estimate of the delivery date. Notify each customer in advance of the delay, and blame the delay on unforseen circumstances beyond your company's control. Notify each customer in advance of the delay, and provide an updated estimate of the delivery date. Apologize to any customer that calls to complain about the delay, and blame the delay on unforseen circumstances beyond your company's control.