Dr. Walker constantly tries to strong-arm you into providing quicker turnaround and, despite the fact that you've given him a disproportionate amount of attention in the last few months, he still has the highest remake factor among all of your clients. Now that you've refused to cave in to his latest demand, he's threatening to switch labs.
No matter how committed you are to servicing your customers, you will inevitably run across a dentist who is "satisfaction-resistant." Perhaps you've done some special favors for him in the past and now he expects those favors on a regular basis. Or maybe, no matter how much you try, you just can't seem to please him.
When you're faced with a client who can't be satisfied and won't recognize when you've extended yourself, you have to consider whether or not he is a good "fit" for your business. If your efforts to be service-oriented are constantly resulting in frustration, you may decide that the amount of time and emotional energy you expend on serving that client just aren't worth the income he generates.
Of course, if you have several disgruntled customers, then you need to take a close look at your laboratory's operation and the manner in which you interact with dentists. If you have just the occasional "Dr. Walker," don't beat yourself up. Accept that there will always be people for whom satisfaction is an elusive concept; focus your energies on more positive, mutually beneficial customer relationships.