on going brake noise

I went in to replace tyres and while replacing the tyres the manager notified me that my brake pads were almost worn out. I checked the pads and they were so i decided to have the pads replaced and the sand the discs flat. 1 hour later i was done with new tyres and brakes. A week later i started hearing noises everytime i brake. It made a knocking sound everytime i braked. I went back and asked them to have a look. They looked to see if all the bolts were tight. They checked and said everything is fine. The next day it sounded like something was loose. I went back a few days later as i went away for work and when they checked the brake pads were loose. They said the brake anti rattle clips were worn out and i must replace them. I tried to buy those clips from the agents but they said it comes with the brakes. I went back to see them and the manager organised me the clips. They put in the clips and the sound was gone for 2 days and now it is back. It is getting louder by the day and do not know what to do anymore.