If we look at this from a purely business point of view, then it depends on how successful your business is and your relationship with these customers.
If your business is well established in its market, makes a healthy profit and retains its customer base, then you can afford to be less concerned if you lose customers that appear more trouble than they are worth. On the other hand, if your business is just starting out and trying to establish itself in its target market, then your business may not be able to afford to lose these customers. Instead, you should look at why they’re wasting time and money and address these issues. By analyzing your relationship and history with the customer, you should be able to identify if this is a momentary lapse in reliability or if they will continue to lose you money in the long-term.