Baylor Scott & White The Heart Hospital - Denton

I used this facility for a simple test / exam. We called ahead to have our insurance preapproved and to find out what the cost would be. They quoted $120 and collected that amount at the time of the test. We asked if there would be any additional charges and of course were assured no. A few weeks after the test we received a bill for $475. Upon calling the explanation we were given was "Oh sorry, we looked at the wrong insurance when we quoted you $120." We have no recourse and are now forced to pay the additional $475. How can I be an informed consumer and make choices when I am quoted 80% less than what it will cost me????