Bad breaks. Read reviews before buying

In January 2006 we decided that we need a bigger car, so we bought a brand new 2005 Kia Sedona. Just 2500 miles later we started to have break problems. I searched the internet and found many complaints referring to this particular issue. We have the warranty and had the car serviced 6 times already. It seems that all we do is getting ready to go to have the car serviced, and waiting for the car. They have no idea what is wrong.