In my experience the best practice was to put all the customer-related workflow-parts into one departement (call it Cust.Serv. Dept.) and organise it to work as one or more teams. These teams should have definite tasks, roles and responsibilities. If the responsibilities are belong to groups which are akting like a real team, they will cover all the problems of individuals. I always called the team to account the tasks, or deadlines, or other required parameters. It was working. The key is the real team, with right people in.