I think , if you flowchart your delivery process for your product, you will find that the Sales Dept is an integral and essential component. Simply by completing the cycle by handling customer complaints, the sales dept provides 'opportunities for improvement', which are an important part of the quality system. The fact that the sales dept has it's own policies might be indicative of a problem,in itself. Closer liaison of sales, design and manufacturing departments can lead to better identification of customer needs, and a better product which can be built or manufactured. Uncoordinated policies can work against this approach. I cannot see how you can leave the sales dept out of the loop.