Calipers

I had my calipers replaced four times in the front and twice in the back. When the calipers was replaced, my pads was replaced too. I smelt the same smell and decided to take my vehicle to the dealership in 2016 because sometimes you have to use manufacturer parts. The dealership replaced the calipers, pads, rotors, the whole works for $900.00. They assured me it was the calipers. I told them I had replaced them four times and he still insisted it was the calipers. The same smell is back and I took it back to the dealership, with no charge, they told me they repaired the hose. One day later, I smelt the odor again and took it back. They said they took the whole front system off and cleaned it. One day later the smell was back. I am in the process of taking it back. What could be the problem because I am exhausted from taking my vehicle back and forth. Can someone please help me?