Toyota Corolla SE 2004, 2 wheel drive

This past Monday, my car was in the shop for new brake pads and checking the rotors. It was not making any noise at that time. Since the brake pads were replaced and the rotors were turned, the right front wheel has been making a "clacking sound" when I press the brake pedal, as I am slowing down. It seems even louder when I'm going down hill, as I'm braking.

My husband took the car back to the repair shop today, and they claimed it was a loose wheel cover; however, re-fitting the wheel cover did not solve the problem because it is still making the clacking sound when the brake pedal is pressed and the car is slowing. What is wrong?

Thank you!