You may not actually have uncontrolled hypertension. For instance, if your blood pressure is elevated only at your doctor's office, you might have white-coat hypertension. These temporary spikes could make it seem like you don't have your blood pressure under control when you actually do. Talk to your doctor about home monitoring or ambulatory monitoring, which requires that you wear a portable blood pressure device for a day.
In addition, be sure the correct blood pressure cuff is used when you get checked at the doctor's office. A cuff that's not appropriate for you can provide an inaccurate measurement. If your arm is very large, for instance, a standard-size blood pressure cuff may be too small and provide inaccurate readings.