What actions must be taken to ensure there's no disruption to customer satisfaction?

generally, customer satisfaction comes from knowing your customers needs, wants and behaviors. you can ensure they are satisfied by making sure under any conditions that those are met-through proper staffing (trained and adequate numbers of them) of consumer-facing personnel, distribution channel that ensures your product gets to the right place at the right time; quality product; pricing, innovation.

customers ARE the equation-without them, you have no business.

It seems that you are in the process of acquiring a new company or an SBU of a company. The best way to manage customer satisfaction is to keep them informed and manage their expectations and fears.

Having been in the area of M&A for the past 15 years I can tell you that management of customer relationships is paramount specially if you are going to depend on that customer base for continuous revenue streams from direct contributions or indirect incrimental business.

Keep them informed, in the loop, keep the reps or calling center in place if the business involves heavy ongoing customer support. Manage the cultural change while merging functions of the old and new companies and management styles.