Service and Repairs quality is not good enough,,

In July 2015 my husbands Discovery 3 went in for major service, they phoned and recommended they change the brake pads, so we did, costing us R5000 above the service price extra. A day after we received it my husband found the wheel nut used to loosen the nuts still on one of the wheel nuts and the worst was the noise and feeling of the brakes. When you brake it feels like a fast thump under your foot and sounds like water boiling. its a terrible feeling. I took it back this past Thursday so they can have a look but could not find anything wrong, actually told me it cant be the brakes, and I was off again with a very bad feeling as its not supposed to be like this, it was fine before the service. Last night on my way home, come down a hill the brake was not well at all, as if it was not braking properly. So I phoned this morning to make a arrangement to bring it back in the week for the whole day. Then this afternoon on my way home the brakes just failed twice, and when I come to a dead still it recovers. This was too much and returned it to them immediately. By arriving they again wanted a quick look and I just said to keep it there and sort it out. So lets see the effort.