http://www.usna.usda.gov/Newintro/skypenc1.html
It doesn't look like this particular holly is going to overgrow the corner. In fact, it seems like the perfect tree for such a small space. And it seems to need very little maintenance beyond watering.
It would help if you could post a picture of your tree, so we can understand what you don't like about it.
Maybe you're in the wrong climate zone (too hot? too cold?) and for that reason the tree isn't doing well?