The amount of a manager's time (and the company's money) that any employee is entitled to is directly proportional to the amount of revenue that that employee creates or the amount of spend that that employee saves.
Simple, clear, appropriate. Notice that I do not use the word 'fair'. Fair is a fuzzy term; its definition depends upon who is speaking, and never the twain shall meet. But 'appropriate' is something that we can agree on, even if neither side particularly likes it.
Take a look at how your Customer Service and Business Development teams are comped. If your organization is like most, the first is too low and the second is much too high. And I know that the next words out of your mouth are these: "How can we compete for BD reps if we pay below the going rate?"
First, half the reason that you need BD reps is that you lose Customers because they don't receive Customer for Life service. Fix that - maybe by increasing retention among your CS reps and comping them for hitting Customer retention goals - and half of your BD needs go away.
Second, you are not looking for BD divas; you want BD reps who consistently hit 100% of goal (not above or below that) and who take the long view that taking care of Customers up front leads to more and better referrals which leads to higher revenue which leads to more money.
When you comp by value, there is less jealousy and distraction from doing work, because the math is there for all to see: Produce more or save more = get more.
You can't fulfill the American dream any simpler than that.