Before we can begin to sort out how to approach this situation it's appropriate to identify the relevant stakeholders and their motivations. There is a also a video
for this insight which is a component of the Effective Problem Solving Course
Given the relationship diagram developed to this point the stakeholders would seem rather easily identified.
Management is focused on development of the corporation and their bonuses.
The Sales Dept is focused on meeting their sales goals, keeping their jobs and bonuses.
The AR department is very focused on management's demands since the last department was fired.
Customers are most concerned about the health and well being of their business.
Many of these points of focus would appear to be going in opposing directions sort of like the conflicting goals of the diagram.
So how do arrive at an approach that improves things for all the stakeholders?