Brake Pads Making noise

In May I had my disk and brake pads changed. since then I haven't had peace driving my car. It makes noises as if the brake pads are finished. Just after changing the brake pads, I went back to complain about the noise and I was told that after 300km it should be fine but it is not. I went after the 300km and now I was told that this is an issue that they are experiencing with all the renault cars. This is very uncomfortable as I do not know what risk I am in. I am driving a car that makes bad noises as if something is going to brake. I am always concerned about my safety in this car.